Sahih al-Bukhari 7503
Narrated Zaid bin Khalid:
It rained (because of the Prophet's invocation for rain) and the Prophet (ﷺ) said, "Allah said, 'Some of My 
slaves have become disbelievers in Me, and some others, believers in Me.'"
حَدَّثَنَا مُسَدَّدٌ، حَدَّثَنَا سُفْيَانُ، عَنْ صَالِحٍ، عَنْ عُبَيْدِ اللَّهِ، عَنْ زَيْدِ بْنِ خَالِدٍ، قَالَ مُطِرَ النَّبِيُّ صلى الله عليه وسلم فَقَالَ ‏
"‏ قَالَ اللَّهُ أَصْبَحَ مِنْ عِبَادِي كَافِرٌ بِي وَمُؤْمِنٌ بِي ‏"‏‏.‏