Abu Dharr (RAA) narrated that the Messenger of Allah (ﷺ) said: “Do not consider any act of goodness as being insignificant even if it is meeting your brother with a cheerful face.” Related by Muslim.
Benefits: No righteous deed is insignificant. Allah the Exalted has said: «وَمَاتَفْعَلُوامِنْخَيْرٍفَإِنَّاللَّـهَبِهِعَلِيمٌ»[2-البقرة:215] “And whatever good you do, Allah knows it.” And He said: «فَمَنيَعْمَلْمِثْقَالَذَرَّةٍخَيْرًايَرَهُ»[99-الزلزلة:7] “So whoever does an atom’s weight of good will see it.”
Source: Sharh Bulugh al-Maram min Adillat al-Ahkam, Kitab al-Jami', Page: 92