Silsilah as-Sahihah 799 — Making up deficiencies in obligatory prayers

It is narrated from Sayyiduna ‘Aidh bin Qurt (may Allah be pleased with him) that the Noble Prophet (peace and blessings of Allah be upon him) said: "Whoever performs an (obligatory) prayer and does not complete it, then its deficiency will be made up through his voluntary prayers."