Musnad Ahmad 790:158

Yazid narrated to us, Hammam informed us, and 'Affan and 'Abd al-Samad said: Hammam narrated to us, from Qatadah. 'Affan said in his narration: He said: 'Imran ibn 'Isam al-Dab'i narrated to me. And Yazid said: From Qatadah, from 'Imran ibn 'Isam al-Dab'i, from an elder from the people of Basra, from 'Imran ibn Husayn, from the Prophet, peace and blessings of Allah be upon him, regarding the saying of the Almighty, "And the even and the odd" (al-shaf'i wa al-watr): He said: "It is the prayer; some of it is even, and some of it is odd."