Musannaf Ibn Abi Shayba 3:5767

Waki’ narrated to us, he said: Al-A’mash narrated to us, from Khaythama, he said: Al-Harith ibn Qays al-Ju’fi went out. When he went out from the houses, he shortened the prayer. It was said to him: "Do you shorten the prayer?" He said: "I will complete it today and shorten it tomorrow."