I heard the Messenger of Allah ﷺ say, "Do not curse Tubba, for he had indeed accepted Islam."
حدثنا حسن حدثنا ابن لهيعة حدثنا أبو زرعة عمرو بن جابر
سمعت رسول الله ﷺ يقول لا تسبوا تبعا فإنه قد كان أسلم
No references are available.
Its chain is daif because of Amr bin Jabir, who alone transmitted this report, though an unknown narrator corroborated him, as noted by Haythami, 8/76. However, he said, "Amr bin Jabir is a liar." The hadith is also found in Tabarani's Al-Kabir, 11/296, no. 11790.