Sahih Muslim · Hadith 1798

وحدثنا ابن المثنى، وابن، بشار قالا حدثنا محمد بن جعفر، حدثنا شعبة، عن أنس بن سيرين، قال سألت ابن عمر ‏.‏ بمثله وزاد ويوتر بركعة من آخر الليل ‏.‏ وفيه فقال به به إنك لضخم ‏.‏

Ibn 'Umar reported Allah's Messenger (may peace be upon him) as saying: The night prayer consists of pairs and when you see the approach of dawn, make this number odd by one rak'ah. It was said to Ibn 'Umar: What does the (word) pair imply? He said: (It means) that salutation is uttered after every two rak'ahs.

Gradings are classical jarḥ-wa-taʿdīl, name-matched to a rijāl index (not individually re-verified).