Musnad Abu Ya'la al-Mawsili 219:16

Harun ibn Ma'ruf narrated to us, Yahya ibn Sulaym narrated to us, he said: I heard Muhammad ibn Sa'id al-Mu'adhdhin, from Abdullah ibn 'Anbasah, he said: I heard Umm Habibah bint Abi Sufyan saying: The Messenger of Allah (may Allah bless him and grant him peace) said: "Whoever maintains four rak'ahs before the 'Asr (prayer), Allah the Almighty and Majestic will build a house for him in Paradise."