وَوَهَبْنَا لَهُ إِسْحَاقَ وَيَعْقُوبَ نَافِلَةً (And We blessed him with Ishaq and Ya` qub as gift - 21:72) That is, Allah Ta` la had bestowed upon him the son Ishaq (علیہ السلام) as per his supplication and in addition to that a grandson Ya` qub (علیہ السلام) as a gift. This is why he is referred to as نَافِلَةً nafilah which originally means 'extra'.
- 21:7373
وَجَعَلْنَاهُمْ أَئِمَّةً يَهْدُونَ بِأَمْرِنَا وَأَوْحَيْنَا إِلَيْهِمْ فِعْلَ الْخَيْرَاتِ وَإِقَامَ الصَّلَاةِ وَإِيتَاءَ الزَّكَاةِ ۖ وَكَانُوا لَنَا عَابِدِينَ
And We made them leaders to guide (the people) by Our command; and We inspired them to perform good deeds and observe their moral obligations and pay the zakat; and they obeyed Us.
- common.revelation-Meccan
- common.hizb : 131