Better be a nettle in the side of your friend, than his echo. The condition which high friendship demands is ability to do without it. To be capable of that high office requires great and sublime parts. There must be very two before there can be very one.
Emerson
No friendship can excuse a sin.
Jeremy Taylor
Friendship is to be purchased only by friendship. A man must have authority over others, but he can never have their heart but by giving his own.
Thomas Wilson
True friends visit us in prosperity only when invited, but in adversity they come without invitation.
Theophrastus
Now can there be a worse disgrace than this—that I should be thought to value money more than the life of a friend?