The Quran

وَلا تَكونوا كَالَّذينَ خَرَجوا مِن دِيارِهِم بَطَرًا وَرِئَاءَ النّاسِ وَيَصُدّونَ عَن سَبيلِ اللَّهِ ۚ وَاللَّهُ بِما يَعمَلونَ مُحيطٌ

Muhammad Asad

And be not like those [unbelievers] who went forth from their homelands full of self-conceit and a desire to be seen and praised by men¹ for they were trying to turn others away from the path of God - the while God encompassed all their doings [with His might].

A reference to the Quraysh army which set forth from Mecca under the leadership of Abu Jahl in the conviction that they would destroy the Prophet and his followers. These words imply a warning to the believers, of all times, never to go to war boastfully and for the sake of empty glory.