Silsilat al-Ahadith al-Sahihah

Abu Salih narrates both as Marfu‘ and Mursal that the Messenger of Allah (peace and blessings be upon him) said: "The four Sunnah before the Zuhr prayer become equal to the prayer at the time of Sahar (pre-dawn)."

It is narrated from Sayyiduna Abu Musa (may Allah be pleased with him) that the Noble Prophet (peace and blessings of Allah be upon him) said: "Whoever offers four rak‘ahs of Duha prayer and four rak‘ahs before Zuhr, a house will be built for him in Paradise."