(11) بَابُ قَوْلِ اللَّهِ تَعَالَى: {هَلْ تَرَبَّصُونَ بِنَا إِلاَّ إِحْدَى الْحُسْنَيَيْنِ} وَالْحَرْبُ سِجَالٌ
Narrated `Abdullah bin `Abbas:
That Abu Sufyan told him that Heraclius said to him, "I asked you about the outcome of your battles with him (i.e. the Prophet (ﷺ) ) and you told me that you fought each other with alternate success. So the Apostles are tested in this way but the ultimate victory is always theirs.
Reference: Sahih al-Bukhari 2804
In-book reference: Book 56, Hadith 21
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 4, Book 52, Hadith 60