(2) بَابُ قَوْلِ اللَّهِ تَبَارَكَ وَتَعَالَى: {قُلِ ادْعُوا اللَّهَ أَوِ ادْعُوا الرَّحْمَنَ أَيًّا مَا تَدْعُوا فَلَهُ الأَسْمَاءُ الْحُسْنَى}
Narrated Jarir bin `Abdullah:
Allah's Messenger (ﷺ) said, "Allah will not be merciful to those who are not merciful to mankind."
Reference: Sahih al-Bukhari 7376
In-book reference: Book 97, Hadith 6
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 9, Book 93, Hadith 473