Muwatta Malik · Hadith 393

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ نَافِعٍ، أَنَّ ابْنَ عُمَرَ، لَمْ يَكُنْ يَلْتَفِتُ فِي صَلاَتِهِ ‏.‏

Yahya related to me from Malik from Nafi that Ibn Umar would never turn around when praying

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