Nafi' said that ‘Abdallah b. ‘Umar used to see his son ‘Ubaidallah saying supererogatory prayers while on a journey, and did not express disapproval. Malik transmitted it.

وَعَنْ نَافِعٍ قَالَ: إِنَّ عَبْدَ اللَّهِ بْنَ عُمَرَ كَانَ يَرَى ابْنَهُ عُبَيْدَ اللَّهِ يَتَنَفَّلُ فِي السَّفَرِ فَلَا يُنْكِرُ عَلَيْهِ. رَوَاهُ مَالِكٌ