In the name of Allah, Most Gracious, Most Merciful.
Abu Sufyan Sakhr bin Harb (May Allah be pleased with him) mentioned Heraclius in a long Hadith and said: Heraclius asked me: “What does this Prophet (SAWS) teach you?” I said: “He orders us to worship Allah Alone and not to associate a thing with Him in worship, to discard what our ancestors said (in false beliefs), to perform the Salat (prayer), speak the truth, and maintain the ties of kinship”. (Al-Bukhari and Muslim).
Commentary: Besides Tauhid (Oneness of Allah), this Hadith enjoins punctuality in Salat and excellence of character. In all the forms of worship, Salat is the most important, and the best in the nobility of character is righteousness. After professing faith in Tauhid and belief that Muhammad (SAWS) is the last Prophet of Allah, a Muslim should be punctual in Salat and make himself a model of excellent character.
Note: Abu Sufyan was not a Muslim when he gave that statement to Heraclius, at the time he was one of the enemies of Islam. May Allah guide us to the straight path. Ameen.
SAWS: May Allah exalt his mention and protect him from imperfection
Riyaadiss-Saliheen (The Meadows of the Righteous)
By Imam An Nawawi
Chapter 40, Page 109, No 327