Hadith: O Messenger of Allah, who is the best among people?

عن أبي سعيد الخدري رضي الله عنه مرفوعاً: قال رجلٌ: أي الناسِ أفضل يا رسول الله؟ قال: «مؤمنٌ مجاهدٌ بنفسِه ومالِه في سبيل الله» قال: ثم مَن؟ قال: «ثم رجلٌ معتزلٌ في شِعب من الشِّعَاب يعبدُ ربَّه، ويدعُ الناسَ من شره». وفي رواية: «يتقِي اللهَ، ويدعُ الناسَ مِن شَره».
[صحيح] - [متفق عليه، والرواية الثانية لفظ البخاري]

Abu Sa‘īd al-Khudri (may Allah be pleased with him) reported that a man said: “O Messenger of Allah, who is the best among people?” He said: “A believer who strives in the cause of Allah with his life and wealth.” He said: “Then who?” He said: “A man who retires to a narrow valley to worship his Lord.” In another version: “A man who is conscious of Allah and safeguards people against his evil.”
[Authentic hadith] - [Al-Bukhari and Muslim. This is the wording of Muslim]

Explanation

The Prophet (may Allah's peace and blessings be upon him) was asked who the best of men is. He stated that it is the man who strives in the cause of Allah with his wealth and his life. When asked about the next best man, the Prophet (may Allah's peace and blessings be upon him) said: "It is the man who isolates himself in a valley to worship Allah and let people be safe from his evil." This means that the man is busy worshiping Allah, keeping away from people, and preventing his evil from coming to them.