Ibn ‘Abbas said that God’s Messenger used to glance right and left during prayer but did not turn his neck to look behind him. Tirmidhi and Nasa’i transmitted it.

وَعَنِ ابْنِ عَبَّاسٍ رَضِيَ اللَّهُ عَنْهُمَا قَالَ: إِنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ كَانَ يَلْحَظُ فِي الصَّلَاةِ يَمِينًا وَشِمَالًا وَلَا يَلْوِي عُنُقَهُ خَلْفَ ظَهْرِهِ. رَوَاهُ التِّرْمِذِيُّ وَالنَّسَائِيُّ