Oneness, Uniqueness of Allah (Tawheed)
حَدَّثَنَا مُحَمَّدُ بْنُ كَثِيرٍ، حَدَّثَنَا سُفْيَانُ، عَنِ الأَعْمَشِ، عَنْ أَبِي وَائِلٍ، عَنْ أَبِي مُوسَى، قَالَ جَاءَ رَجُلٌ إِلَى النَّبِيِّ صلى الله عليه وسلم فَقَالَ الرَّجُلُ يُقَاتِلُ حَمِيَّةً وَيُقَاتِلُ شَجَاعَةً وَيُقَاتِلُ رِيَاءً، فَأَىُّ ذَلِكَ فِي سَبِيلِ اللَّهِ قَالَ " مَنْ قَاتَلَ لِتَكُونَ كَلِمَةُ اللَّهِ هِيَ الْعُلْيَا، فَهْوَ فِي سَبِيلِ اللَّهِ ".Narrated Abu Musa:A man came to the Prophet (ﷺ) and said, "A man fights for pride and haughtiness another fights for bravery, and another fights for showing off; which of these (cases) is in Allah's Cause?" The Prophet (ﷺ) said, "The one who fights that Allah's Word (Islam) should be superior, fights in Allah's Cause." (See Hadith No. 65, Vol)
From Sahih al-Bukhari, whose reports the scholars accept as authentic.