Musannaf Ibn Abi Shaybah 6118 — The reward of one who keeps to twelve

It is narrated from Sayyidah Umm Habibah (may Allah be pleased with her) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever prays four rak'ahs before Zuhr and four after Zuhr, Allah Almighty makes him forbidden to the Fire."