عن أنس رضي الله عنه قال: لقي رسول الله صلى الله عليه وسلم أبا ذر فقال: يا أبا ذر ألا أدلك على خصلتين هما أخف على الظهر وأثقل على الميزان من غيرهما قال: بلى يا رسول الله قال: عليك بحسن الخلق وطول الصمت فوالذي نفسي بيده ما عمل الخلائق بمثلهما (الترغيب والترهيب الرقم: 4022)
Hazrat Anas (radhiyallahu ‘anhu) reports that on one occasion, Rasulullah (sallallahu ‘alaihi wasallam) met Hazrat Abu Zar (radhiyallahu ‘anhu) and said to him, “O Abu Zar! Shall I not show you two qualities which are light on the back (i.e. they do not require much effort to carry out), yet they are heavier on the scale (of good deeds) than other good actions?” Hazrat Abu Zar (radhiyallahu ‘anhu) replied, “Certainly inform me, O Rasul of Allah (sallallahu ‘alaihi wasallam)!” Rasulullah (sallallahu ‘alaihi wasallam) then said, “Firmly hold on to good character and remain silent for lengthy periods, for I take an oath by that Being in whose hand lies my life – the creation cannot carry out any good action which can equal these two good actions.”
Note: Good character refers to fulfilling the rights of Allah Ta‘ala and the creation, and making sabr and enduring at the time of hardship and difficulty, as well as expressing shukr and gratitude to Allah Ta‘ala and the creation respectively at the time of enjoying prosperity and ease, or any type of benefit through people. It is for this reason that the Hadith has praised this quality and explained that it will weigh heavy on the scales on the Day of Qiyaamah.
As far as remaining silent for lengthy periods is concerned, then the meaning of the Hadith is that one remains silent while reflecting and pondering over the favours of Allah Ta‘ala and His kindness upon oneself, or one reflects over his weaknesses and turns to Allah Ta‘ala in remorse and repentance.
Apart from this, remaining silent is an effective way to save oneself from falling into sins which pertain to the misuse of the tongue. Hence, when there is no need to speak, one should remain silent.