Is it permissible to accept a gift from a Muslim who has unlawful earnings?
The answer
If the majority of a Muslim’s wealth is accrued from halāl transactions, then it will be permissible to accept the gift from such a Muslim. If half or more of a Muslim’s wealth is accrued from impermissible investments, then one should abstain from accepting gifts from such a person.[1]
Condition: Permissible if most of the giver's wealth is halal; avoid if half or more is unlawful.
Explanation
It is improper to question a Muslim or investigate the source of a Muslim’s income if there is no reason to cause doubt.2
And Allah knows best.
Mufti Faraz Adam
References
1آكِلُ الرَّبَّا وَكَاسِبُ الْحَرَامِ أَهْدَى إلَيْهِ أَوْ أَضَافَهُ وَغَالِبُ مَالِهِ حَرَامٌ لَا يَقْبَلُ، وَلَا يَأْكُلُ مَا لَمْ يُخْبِرْهُ أَنَّ ذَلِكَ الْمَالَ أَصْلُهُ حَلَالٌ وَرِثَهُ أَوْ اسْتَقْرَضَهُ، وَإِنْ كَانَ غَالِبُ مَالِهِ حَلَالًا لَا بَأْسَ بِقَبُولِ هَدِيَّتِهِ وَالْأَكْلِ مِنْهَا، كَذَا فِي الْمُلْتَقَطِ. (الهندية ج 5 ص 343 الرشيدية)
إمداد الفتاوى ج 4 ص 119 مكتبة دار العلوم كراتشي
2فتاوى محمودية ج 18 ص 133
Based on the Hanafi school and on the question as it was asked. Another mufti may reach a different conclusion. Read the disclaimer.