Reveal not every secret you ...

Reveal not every secret you have to a friend, for how can you tell but that friend may hereafter become and enemy. And bring not all mischief you are able to upon an enemy, for he may one day become your friend.
Reveal not every secret you have to a friend, for how can you tell but that friend may hereafter become and enemy. And bring not all mischief you are able to upon an enemy, for he may one day become your friend.
 Saadi

More phrases

If one does not know to which port one is sailing, no wind is favorable.
What a distressing contrast there is between the radiant intelligence of the child and the feeble mentality of the average adult.
We are masters of the unsaid words, but slaves of those we let slip out.
I have always found that mercy bears richer fruits than strict justice.
A lie gets halfway around the world before the truth has a chance to get its pants on.

Quotes from the same author

When a mean wretch cannot vie with another in virtue, out of his wickedness he begins to slander. The abject envious wretch will slander the virtuous man when absent, but when brought face to face his loquacious tongue becomes dumb.
Patience accomplishes its object, while hurry speeds to its ruin.
Oman overall has great animal and plant biodiversity because it has mountains, desert, coastal areas and rich coral reefs.
To be over much facetious is the accomplishment of courtiers and blemish of the wise.
Riches are for the comfort of life, and not life for the accumulation of riches. I asked a holy wise man, "Who is fortunate and who is unfortunate?" He replied: "He was fortunate who ate and sowed, and he was unfortunate who died without having enjoyed.