Harb ibn Ubaydullah ibn Umayr ath-Thaqafi told on the authority of his grandfather, a man of Banu Taghlib: I came to the Prophet ﷺ, embraced Islam, and he taught me Islam. He also taught me how I should take sadaqah from my people who had become Muslim. I then returned to him and said: Messenger of Allah, I remembered whatever you taught me except the sadaqah. Should I levy tithe on them? He replied: No, tithes are to be levied on Christians and Jews.  

أَتَيْتُ النَّبِيَّ ﷺ فَأَسْلَمْتُ وَعَلَّمَنِي الإِسْلاَمَ وَعَلَّمَنِي كَيْفَ آخُذُ الصَّدَقَةَ مِنْ قَوْمِي مِمَّنْ أَسْلَمَ ثُمَّ رَجَعْتُ إِلَيْهِ فَقُلْتُ يَا رَسُولَ اللَّهِ كُلُّ مَا عَلَّمْتَنِي قَدْ حَفِظْتُهُ إِلاَّ الصَّدَقَةَ أَفَأُعَشِّرُهُمْ قَالَ لاَ إِنَّمَا الْعُشُورُ عَلَى النَّصَارَى وَالْيَهُودِ