Here are 110 Gaelic proverbs and sayings in English translation. They are culled from Gaelic Proverbs and Proverbial Sayings, with English Translations by Thomas Donald MacDonald. His book was published in 1926. This is a shortened version of the book.
The following ideas are from MacDonald's introduction:
He rides slowly who observes.
The heaviest ear of corn bends its head the lowest.
The weed that's on the dunghill growing
Will its head he highest showing.
The highest mountain in the land
Is oftenest covered with mist.
Going to ruin is silent work.
A poor fellow can do but his best.
Death-bed repentance is like sowing seed at Martinmas (on 11 November).
Quiet humour, shrewd insight, and homely truths with a large measure of deductive philosophy are enshrined in the proverbs.
In his introduction to his selection of Gaelic proverbs and sayings, Thomas D. MacDonald writes that there are writers who say that the Celtic races were not much given to proverbs, and others who tell a different story.
MacDonald asserts that the Highlander finds the proverbs very useful in conversation, and frequently quotes them to good purpose.
Lord John Russell defined the proverb as "the wisdom of many and the wit of one."
If there is one medium more than another that will perpetuate for us the wit and wisdom of our forefathers . . . when mother wit and native shrewdness took the place of present-day sharpness, that medium is the proverb.
We do have a considerable number that are characteristically Highland; and probably cannot be understood apart from the Highlands and the Highland people. The bulk of Gaelic proverbs are the product of the thatched cottages, and not of the baronial halls. Yet a considerable amount of proverbs are the product of the better-to-do of the days of old.
Sheriff Nicholson published 3900 proverbs in 1882. MacDonald's volume is indebted to the worthy Sheriff's patriotic achievement to a considerable extent. Out of nearly 4000 Gaelic proverbs and proverbial sayings, known as current in the Highlands, including native and borrowed, the number included in MacDonald's work is limited.
In MacDonald's work, English equivalents are adopted along with the Gaelic proverbs.
The present extracted work is a shortened version of MacDonald's work. Most of the proverbs here are numbered as he does, for easy reference. Unnumbered proverbs here, are not numbered by him. Only a fraction of MacDonald's proverbs are included. As a rule of the thumb, many otherwise well-known proverbs have been left out, explanations are kept to a minimum, and only English renderings of Gaelic proverbs are given.
- T. K.
Part 1. Miscellaneous
Say but little and say it well. 
During the year when meal is scarce let big bakings be few. 
All dogs down on the strange dog. 
The oar that's nearest at hand, row with it. 
He who will not prosper in his sleep, will not prosper when awake. 
The more you get of what's good, the less you will get of what's bad. 
The herb that cannot be found will not give relief. 
Who farthest away ever did roam, heard the sweetest music on returning home. 
What is well done will be shown by results. 
When we are seeking gold, let us be seeking gold; And when we are seeking bait let us be seeking bait. (i.e., One thing at a time, and everything in its own time.) 
Who keeps not his arms in times of peace, will have no arms in times of war. 
The worst cow in the fold lows the loudest. 
Necessity will get something done. 
One man can lead a horse to the water, but twelve cannot make it drink. 
A black ewe may have a white lamb. 
Better be silent than sing a bad song. 
Felicity follows generosity. 
Have the caution of a thief over every one, but make no one a thief. 
The little frequent [may] overtake the infrequent large. 
No fumes from the pot, but from what it contains. 
Gentility will not boil the pot. 
There is no deceit so great as a promise unfulfilled. 
One hapless act may undo a man, and one timely one will re-establish him. 
Buy according to your needs, and sell as you may desire. 
Friendship conceals blemishes. 
Vanity is not without trouble. 
A poor fellow can do but his best. 
Despise your old shoes when you get your new ones. 
Industry pays debt. 
The heavy burden of the lazy man. 
Gold itself may be too dearly bought. 
Where the river is shallowest It will make the most noise. 
The cat may look at the king. 
See that your own hearth is swept before you lift your neighbour's ashes. 
A hasty judgment may be harmful. 
Even the ravens must live. 
May the Lord preserve the moon from the dogs. 
May we be preserved from lawyers and from doctors. (Truly a very fervent wish, this one.) 
Sweet words beguile a fool. 
Although the wren be small it will make a noise. 
A wicked woman will get her wish, but her soul will not get mercy. 
Slippery is the flagstone (doorstep) at the mansion house door. (A hint of the uncertainty of depending on favours from those in high places, and that one's own efforts should be depended upon as the means to success. There are, however, exceptions to.) 
Hesitation in buying is better than delay in paying. 
"It is less for that," as the wren said when it took the full of its bill from the large lake. 
Ignorance is a great burden. 
A timely advice [may be far] better than a late gift. 
The raven thinks its own chic the prettiest. 
Bought wit [can be] best. 
Two heads are better than one. 
Better be sure than be a loser. 
The upright heart endures a great deal before it breaks. 
Better be alone than in bad company. 
It's difficult to put an old head on a young shoulder. 
Empty bladders are loquacious. (An empty pail makes most noise.) 
Woe to him who is not afraid of falsehood. 
The mouth will speak, but deeds are the proof. 
Let the dead lie. 
Bad conversation spoils good manners. 
A rich heart may he under a poor coat. [Partial] 
The slow horse [may] reach the mill, but the one that breaks its bones [may] not. 
Consider well in the first place, then act. 
The waves have some mercy, but the rocks have no mercy at all. 
"There is meat and music here," as the fox said when running away with the bagpipes. 
Part 2. Men, Women, Marriage
Throughout Gaelic proverbs there is a vein of quiet humour that belies the charge that the Highlander is wanting in that saving grace.
Who speaks ill of his wife dishonours himself. 
He who marries a wife marries trouble. (Sheriff Nicolson says: "I have found no Gaelic proverb expressing anything more unfavourable to marriage than this one.") 
A friend's counsel, unasked, is never esteemed as it ought to be. 
Wooing is a costly dame. 
Everyone can rule a shrew except the one she's married to. 
Anger may look in on a wise man's heart, but it abides in the heart of a fool. 
Woman's patience - till you count three. (This is pointed, and pithy, and true - sometimes. It bears the stamp of the Gael's manner towards women. Gaelic proverbs can be sarcastic to a degree.) 
Though the raiment be not the man, he is no man without it. 
Much may be done under the guidance of a good man. 
Better be bordering on plenty than be in the middle of poverty. 
It is difficult to track a man through a river. 
The hurried marriage is often a tragedy, and the slow to marry are often blind. (There seems nothing left here but to take one's chance by risking it.) 
Worst of all things, a bad wife. 
Meal is finer than grain, women are finer than men. (The Gael regards woman as of finer mould, of more tender sensibility, therefore he is deferential towards her. However, he is not insensible to her faults.) 
Choose the good mother's daughter were the Devil her father. 
"When you see a well-bred woman,
Catch her, catch her;
If you don't do it,
Someone else will match her." – Burns 
If you are manly, don't be gloomy. 
What the little ones will see the little ones will do, and what they hear they will repeat. 
The disdainful (high) look of the old maid. 
Marriage will sober love. 
Choose a bird from a clean nest. 
Part 3. Weather and Season Lore - Object Lessons from Nature - the Deity - the Devil
"Mountains are the great cathedrals of the earth, with their gates of rock, pavements of clouds, choirs of stream and stone, and altars of snow."
One of the earliest proverbial sayings associated with the Celts is recorded in the Third Book of the Ethics of Aristotle, from 400 B.C. Here it is recorded that it was even then a proverbial saying of the Celts of Asia Minor, that "They feared neither an earthquake nor a storm on the sea."
Weather signs, season lore, and the object lessons of nature, in all their various and varying moods, were observed, and inwardly read with zest and to good purpose. The influence of weather conditions on plants was particularly noticed.
What God has promised man cannot prevent. 
The shamrock is folding its garments before heavy rain. 
The Earl of Mar's cooking bravery
Hunger is a very good cook,
Woe to him who would despise food;
This barley gruel in my shoe heel
Is the best I've found in all my time. 
The original Gaelic lines here quoted are attributed to the Earl of Mar, who commanded the Royal Forces at the first Battle of Inverlochy, in 1411. Mar's forces were routed by Donald Balloch of the Isles and his Highland host, and the Earl was compelled for a time to live the life of a fugitive among the hills of Lochaber and Badenoch. In dire need for food, he approached a humble dwelling where a lonely old man lived. His condition seemed to have been only a little better than that of the earl. All the food he had was some barley meal, and he had not as much as a dish that it could be prepared in.
But the Earl was starving, and took off one of his brogues (shoes), and made barley gruel in it. Having partaken of this homely fare, he expressed his gratitude to the old man by reciting the foregoing lines and invited the old man to come to Mar Castle some time.
Part 4. Land and Labour
He who will not sow, [may] not reap in Autumn. [526, mod]
He who always sets his net will get a bird sometime. 
Sleepy fellow will lose a wedder, but gad-about will lose a cow. 
A late beginning will not mend a bad day's work. 
Where there are no cattle, the king will lose his rights. (Old, from times when all wealth was derived direct from the land, and the King's means too somehow.) 
Though the man be the farmer, the horse is the labourer. 
Better a handful of craftsmanship than a handful of gold. 
Better small corn seeds out of bad land than no seed at all. 
[Good] method will keep a farm. [Partial] 
Necessity made the roe swim across the loch. 
Industry results will bring; sheaves of corn and stacks that fill the barn. [Abr] 
Part 5. The Fingalians
Gaelic legendary heroes are shown as corresponding in character and domestic misfortunes with the legendary King Arthur: "faithful to their friends, generous to their foes, mighty in war, and gentle and wise in peace."
Hereditary gifts are [often] better than acquired ones. [Or: Hereditary gifts may not always be better than acquired ones. Decide that.] 
Part 7. Clans and Clanship
Readers must judge for themselves as to which Clan was best at blowing its own horn. The time when such sayings were in use is now so far off that we can quote many of them with a fat smile now and then.
It is not every day that Macintosh holds a Court. (The Macintosh here referred to was one of the Chamberlains to the Earls of Perth. At these Courts, thieves were hanged – but culprits were not always at hand. The saying relates to these brutal ways.) 
Stewarts, the race of kings and tinkers. (The name was commonly adopted by tinkers for the same reasons that induce Jewish moneylenders to adopt some of our most aristocratic names - mercenary motives and the desire for respectability.)