غفر له - He forgave him.
استغفره - He asked him for forgiveness.
2. Reflexive of the fourth form
The tenth stem often means that the subject of the verb is performing the action denoted by the fourth stem (a) upon himself or (b) for himself; e.g.,
أسلمه - He gave him up./He handed him over.
استسلم - He gave himself up./He handed himself over./He surrendered.
أعدّه - He made it ready.
استعدّ - He made/got himself ready.
أحياه - He brought him to life./He kept him alive.
استحياه - He kept him alive for his own advantage.
It should be borne in mind that the fourth stem often has a declarative meaning. When it does, the tenth stem can be reflexive of this meaning; e.g.,
أوجبه - He made it necessary for others.
استوجبه - He made it necessary for himself.
أحبّه - He loved him.
استحبّه - He loved him for himself, i.e. he preferred him.
(التوبة:23) يَا أَيُّهَا الَّذِينَ آمَنُوا لَا تَتَّخِذُوا آبَاءَكُمْ وَإِخْوَانَكُمْ أَوْلِيَاءَ إِنِ اسْتَحَبُّوا الْكُفْرَ عَلَى الْإِيمَانِ ۚ وَمَن يَتَوَلَّهُم مِّنكُمْ فَأُولَٰئِكَ هُمُ الظَّالِمُونَ
O you who have believed, do not take your fathers or your brothers as allies if they have preferred disbelief over belief. And whoever does so among you - then it is those who are the wrongdoers. (9:23)