Taken from Silsilah Ahadeeth As-Saheehah of Shaykh Al-Albaani Translated by Abbas Abu Yahya
10 - 491 – On the authority of Sa’ad bin Abu Waqqas on the authority of the Prophet -sallAllaahu alayhi wa sallam- who said: ‘If you come to the prayer, come in a tranquil and calm state, pray what you catch and make up what you miss.’ No. 1198