Shama-il Tirmidhi Chapter 34, Hadith Number 2 (217).
A question arises from this hadith, that in that last hadith of the previous chapter, it is stated that Sayyidina Rasoolullah sallallahu alaihe wasallam always remained in deep thought and sorrow. This seems to contradict that hadith. Two explanations are given to the hadith. The first is that the meaning of the hadith is that Sayyidina Rasoolullah sallallahu alaihe wasallam smiled more than he laughed. No other person was seen, whose smile was more than his laugh. In a further hadith which is reported from that same Sahaabi, this has been clearly elucidated. The second explanation is that Sayyidina Rasoolullah sallallahu alaihe wasallam besides being naturally worried, smiled and appeared cheerful so that the Sahaabah radiyallahu anhum might feel at ease and comfortable. This is the pinnacle of humbleness and good character. In the fifth and sixth hadith of this chapter, Sayyidina Jarir radiyallahu anhu says that whenever Sayyidina Rasoolullah sallallahu alaihe wasallam saw me, he met me with a cheerful smile. There now remains no contradiction with the first hadith. Many times it so happens that a person is sad and worried, but to keep others happy, or for some other reason one has the opportunity to meet them cheerfully. Those who have in their hearts a mark of love, experience this many times.