Musnad Ahmad 428:1

Abdullah ibn Ahmad said: Abu Khalid Hudbah ibn Khalid narrated to me, he said: Hammam ibn Yahya narrated to us, he said: Abu Jamrah al-Duba'i narrated to us, from Abu Bakr, from his father, that the Messenger of Allah, peace and blessings of Allah be upon him, said: "Whoever prays the two cool periods (al-bardayn), will enter Paradise."