A fool's bolt is sune shot.
A fool winna gie his toy for the Tower o' London.
A foul foot maks a fu' wame.
"Industry will be sure of a maintenance. A man that carefully goes about his business will have foul feet."—Kelly.
A foul hand maks a clean hearthstane.
A friend at court is worth a penny in the purse.
Kelly's note on this proverb is not favourable to the court usances of his time (1721). "A purse seems to be the only friend at court, for, without that, there is nothing there but neglect and empty promises."
A friend in need is a friend indeed.
A friend to a' is a friend to nane.
"Everybody's friend is nobody's friend."—Spanish.