Sahih Bukhari Volume 3, Book 52, Hadith 2682

حَدَّثَنَا إِبْرَاهِيمُ بْنُ حَمْزَةَ، حَدَّثَنَا إِبْرَاهِيمُ بْنُ سَعْدٍ، عَنْ صَالِحٍ، عَنِ ابْنِ شِهَابٍ، عَنْ عُبَيْدِ اللَّهِ بْنِ عَبْدِ اللَّهِ، أَنَّ عَبْدَ اللَّهِ بْنَ عَبَّاسٍ ـ رضى الله عنهما ـ أَخْبَرَهُ قَالَ أَخْبَرَنِي أَبُو سُفْيَانَ، أَنَّ هِرَقْلَ، قَالَ لَهُ سَأَلْتُكَ مَاذَا يَأْمُرُكُمْ فَزَعَمْتَ أَنَّهُ أَمَرَكُمْ بِالصَّلاَةِ وَالصِّدْقِ وَالْعَفَافِ وَالْوَفَاءِ بِالْعَهْدِ وَأَدَاءِ الأَمَانَةِ‏.‏ قَالَ وَهَذِهِ صِفَةُ نَبِيٍّ‏.‏

Narrated By Abdullah bin Abbas : Abu Sufyan told me that Heraclius said to him, "When I enquired you what he (i.e. Muhammad) ordered you, you replied that he ordered you to establish the prayer, to speak the truth, to be chaste, to keep promises and to pay back trusts." Then Heraclius added, "These are really the qualities of a prophet."