Musnad Ahmad 907:240

'Abd al-Rahman narrated to us, Shu'bah narrated to us, from Simak, from Jabir, who said: "The Prophet, peace and blessings of Allah be upon him, used to recite in the Dhuhr and the 'Asr [prayers] 'By the night when it covers' (Surah Al-Layl). And in the morning [prayer], he would recite longer than that."