Musannaf Ibn Abi Shaybah 4580 — One who leaves having omitted part

It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) led the people in two rak'ahs of the Zuhr prayer and then said the salam. He (peace and blessings be upon him) was asked: "Has the prayer been reduced?" So he (peace and blessings be upon him) led another two rak'ahs and said the salam, then performed the two prostrations of forgetfulness.