Musnad Ahmad 27:1422

Harun narrated to us, Ibn Wahb informed us, I heard Abdullah ibn Umar narrating from Nafi’, from Abdullah ibn Umar, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "Indeed, Allah is Witr (Odd/One) and He loves the Witr." Nafi’ said: And Ibn Umar would not do anything except in odd numbers. *** [Abdullah ibn Ahmad said]: Suwar ibn Abdullah narrated to us, Mu’adh ibn Mu’adh narrated to us, from Ibn ‘Awn, who said: "I saw Ghaylan—meaning the Qadari—crucified at the gate of Damascus."