(Annisa) 4 : 33
وَلِكُلٍّ جَعَلْنَا مَوَالِيَ مِمَّا تَرَكَ الْوَالِدَانِ وَالْأَقْرَبُونَ ۚ وَالَّذِينَ عَقَدَتْ أَيْمَانُكُمْ فَآتُوهُمْ نَصِيبَهُمْ ۚ إِنَّ اللَّهَ كَانَ عَلَىٰ كُلِّ شَيْءٍ شَهِيدًا
And for everyone We have made heir from whatever the parents and close relatives left behind, and to those upon you have pledged, then you give their due portions; indeed Lord Allah is the Witness of everything.
Inheritance is the share which Lord has ordained among the blood relatives as told in verses 8: 75 and 33: 6. One can make bequest one-third of his total property for his adopted sons, grandsons, bosom friends, to the ones suffering from illness, to the ones in distressed conditions, etc. Everything should be done by witnessing the Three-Time-Knower Lord and it should be in Justice Adhikr. See explanation 2: 180, 234, and 4: 7.