Kaysan Abu Sa'id al-Muqbari كيسان أبو سعيد المقبري المدني · General Behavior (Kitab Al-Adab)

When one of you yawns, he should hold his hand over his mouth, for the devil enters.

when you go to your bed while you are in the state of purification. The other said: Perform ablution like the ablution for prayer. He then transmitted the tradition to the effect as Mu’tamir transmitted.

if a man becomes the client of any people without the permission of his patrons (i.e. those who have freed him), on him will be the curse of Allah, of angels and of all people; no obligatory or supererogatory worship will be accepted from him.