Abdullah ibn Abi Hadrat RA

Abdullah ibn Abi Hadrat RA was a new convert whom the Prophet ﷺ sent to spy on Thaqif and the tribes gathering around Ta'if before Hunayn in 8 AH, and who reported an enormous, well-armed host. When Umar RA suggested he was mistaken, Abdullah retorted that Umar had once thought the Prophet ﷺ mistaken too, and the Prophet ﷺ confirmed that Allah had guided Umar from misguidance.