“Is anyone of you incapable, when he prays, of stepping forwards or backwards, or to his right or left?” meaning in order to offer a voluntary prayer. (Using translation from Ibn Mājah 1427)
عَنِ النَّبِيِّ ﷺ قَالَ أَيَعْجِزُ أَحَدُكُمْ إِذَا صَلَّىأَنْ يَتَقَدَّمَ أَوْ يَتَأَخَّرَ أَوْ عَنْ يَمِينِهِ أَوْ عَنْ شِمَالِهِ