Hadith: He who does not thank people in fact does not thank Allah

عَنْ أَبِي هُرَيْرَةَ رَضِيَ اللَّهُ عَنْهُ عَنِ النَّبِيِّ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ قَالَ:
«لَا يَشْكُرُ اللَّهَ مَنْ لَا يَشْكُرُ النَّاسَ»
[صحيح] - [رواه أبو داود والترمذي وأحمد] - [سنن أبي داود: 4811]

Abu Hurayrah (may Allah be pleased with him) reported that the Prophet (ﷺ) said:
"He who does not thank people in fact does not thank Allah."
[Authentic hadith] - [Narrated by Abu Daoud & At-Termedhy & Ahmad] - [Sunan Abu Daoud - 4811]

Explanation

The Prophet (ﷺ) informed that one who habitually does not thank people for the kindness and good they show him does not truly thank Allah because the two are connected. A person whose nature and habit are to be ungrateful to people and fail to thank them will likewise be inclined to be ungrateful for Allah's blessings and neglect showing gratitude to Him.

Benefits from the Hadith

1. The importance of thanking people for the kindness and good they do.
2. The true Bestower of blessings is Allah Almighty, while people are merely means that Allah Almighty employs to whom He wills. Therefore, thanking people is in fact part of thanking Allah Almighty.
3. Thanking people for their kindness is a sign of perfect morals.