Ja’far Ibn Muhammad (rahimahullah) said:

If something that you dislike reaches you about your brother (or he says or does something that upsets you),

then search for one excuse for him up to seventy excuses. If it hits the mark, (then good).

If not, then say, “Perhaps (it was a slip, a mistake and/or) he has an excuse that I am not aware of”.

[al-Jaami' li Shu'ab al-Imaan, Ja’far Ibn Muhammad (rahimahullah), 14/442]

Muhammad Ibn Sireen (rahimahullah) said:

If something reaches you about your brother, then search for an excuse for him. If you do not find an excuse for him, then make an excuse for him!

[al-Jaami' li Shu'ab al-Imaan, 14/441, Muhammad Ibn Sireen (rahimahullah)]

‘Abdullah Ibn Muhammad Ibn Manaazil saod:

The (true) Believer seeks excuses for his brothers, and the hypocrite seeks (and holds onto) the mistakes/faults/slip-ups of his brothers.

[ash-Shu’ab, 7/11197]

Fudayl Ibn ‘Iyyadh (rahimahullah):

Whoever seeks a brother without faults would never have a brother to be his friend.

[Rawdatul ‘Uqaalaa, pg. 169]