Jareer ibn Abdullah reported: The Messenger of Allah, peace and blessings be upon him, said, “Allah will not be merciful to those who are not merciful to the people.”

Source: Sahih Bukhari 6941, Sahih Muslim 2319, Grade: Muttafaqun Alayhi (authenticity agreed upon) according to Al-Bukhari and Muslim

In another narration, the Prophet said, “Verily, Allah is only merciful to His servants who are merciful with others.”

Source: Sahih Bukhari 1224, Grade: Sahih (authentic) according to Al-Bukhari

عَنْ جَرِيرِ بْنِ عَبْدِ اللَّهِ قَالَ قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ لَا يَرْحَمُ اللَّهُ مَنْ لَا يَرْحَمُ النَّاسَ

6941 صحيح البخاري كِتَاب التَّوْحِيدِ بَاب قَوْلِ اللَّهِ تَبَارَكَ وَتَعَالَى قُلْ ادْعُوا اللَّهَ أَوْ ادْعُوا الرَّحْمَنَ أَيًّا مَا تَدْعُوا فَلَهُ الْأَسْمَاءُ الْحُسْنَى

2319 صحيح مسلم كتاب الفضائل باب رحمته صلى الله عليه وسلم الصبيان والعيال وتواضعه وفضل ذلك

وفي رواية أخرى قال وَإِنَّمَا يَرْحَمُ اللَّهُ مِنْ عِبَادِهِ الرُّحَمَاءَ