سنن ابن ماجه

It was narrated that Zaid bin Arqam said: “The Companions of the Messenger of Allah (ﷺ) said: ‘O Messenger of Allah, what are these sacrifices?’ He said: ‘The Sunnah of your father Ibrahim.’ They said: ‘What is there for us in them, O Messenger of Allah?’ He said: ‘For every hair, one merit.’ They said: ‘What about wool, O Messenger of Allah?’ He said: ‘For every hair of wool, one merit.’”