The Prophet ﷺ said: If anyone intercedes for his brother and he presents a gift to him for it and he accepts it, he approaches a great door of the doors of usury.  

عَنِ النَّبِيِّ ﷺ قَالَ مَنْ شَفَعَ لأَخِيهِ بِشَفَاعَةٍ فَأَهْدَى لَهُ هَدِيَّةً عَلَيْهَا فَقَبِلَهَا فَقَدْ أَتَى بَابًا عَظِيمًا مِنْ أَبْوَابِ الرِّبَا