(a) It is narrated from Sayyiduna Anas bin Malik (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever forgets to pray a prayer, let him pray it whenever he remembers it; this is its only expiation."
(b) Qatadah (may Allah have mercy on him) said: "Establish the prayer for My remembrance." [Surah Ta Ha: 14]
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3796