It is reported that a man saw Ibn ʿAbbās – Allāh be pleased with them – holding the tip of his tongue saying:

Woe to you, say what is good and you will reap gain, and be silent from speaking evil and you will be safe.

The man asked him:

O Ibn ʿAbbās, what is the matter that I see you holding the tip of your tongue saying such-and-such?

He replied:

It has reached me that the servant of Allāh will not be as angry at anything on the Day of Resurrection as he will be at his tongue.

Imām Aḥmad, Al-Zuhd p236