the Messenger of Allah said: "A son could not do enough for his father, unless he found him as a slave and purchased him to set him free."  

قَالَ رَسُولُ اللَّهِ ﷺ لاَ يَجْزِي وَلَدٌ وَالِدًا إِلاَّ أَنْ يَجِدَهُ مَمْلُوكًا فَيَشْتَرِيَهُ فَيُعْتِقَهُ