Hadith: A man follows the religion (i.e. ways and manners) of his close friend. So, each of you should carefully consider whom he takes as his intimate friend

عن أبي هريرة رضي الله عنه أَن النبيَّ صَلّى اللهُ عَلَيْهِ وسَلَّم قَالَ:
«الرَّجُلُ عَلَى دِينِ خَلِيلِهِ، فَلْيَنْظُر أَحَدُكُم مَنْ يُخَالِل».
[حسن] - [رواه أبو داود والترمذي وأحمد] - [سنن أبي داود: 4833]

Abu Hurayrah (may Allah be pleased with him) reported: The Prophet (may Allah's peace and blessings be upon him) said:
"A man follows the religion (i.e. ways and manners) of his close friend. So, each of you should carefully consider whom he takes as his intimate friend."
[Hasan] - [Narrated by Abu Dāwūd, At-Tirmidhi, and Ahmad] - [Sunan Abi Dawood - 4833]

Explanation

The Prophet (may Allah's peace and blessings be upon him) pointed out that a person resembles his close friend and companion in his ways and habits, and friendship affects morals, manners, and behaviors. Therefore, he instructed us to choose our friends carefully, as a friend guides his friend to Imān (faith), guidance, and goodness, and helps him in this regard.

Benefits from the Hadith

1. The Hadīth enjoins us to befriend good people and choose them carefully and prohibits us from taking wicked people as friends.
2. He specifically mentioned the friend and not the relative because a person chooses his friends, but has no choice concerning his brothers and relatives.
3. A person should think well before taking anyone as a friend.
4. A person’s religious commitment is strengthened by accompanying the believers and is weakened by accompanying sinners.