The Book of Prayers (Kitab Al-Salat)
Muslim :: Book 4 : Hadith 1903
Jabir b. 'Abdullah reported: Sulaik Ghatafani came on Friday when the Messenger of Allah (may peace be upon him) was delivering the sermon. He (Sulaik) sat down. He (the Holy Prophet) said to him: 0 Sulaik I stand and observe two rak'ahs and make them short, and then said: When any one of you comes on Friday, while the Imam delivers the sermon, he should observe two rak'ahs and should make them short.