After Allah commanded the believers to fight in His cause sincerely and to be mindful of Him, He commanded not to imitate the idolators, who went out of their homes

﴿بَطَراً﴾

(boastfully) to suppress the truth,

﴿وَرِئَآءَ النَّاسِ﴾

(and to be seen of men), boasting arrogantly with people. When Abu Jahl was told that the caravan escaped safely, so they should return to Makkah, he commented, "No, by Allah! We will not go back until we proceed to the well of Badr, slaughter camels, drink alcohol and female singers sing to us. This way, the Arabs will always talk about our stance and what we did on that day.'' However, all of this came back to haunt Abu Jahl, because when they proceeded to the well of Badr, they brought themselves to death; and in the aftermath of Badr, they were thrown in the well of Badr, dead, disgraced, humiliated, despised and miserable in an everlasting, eternal torment. This is why Allah said here,

﴿وَاللَّهُ بِمَا يَعْمَلُونَ مُحِيطٌ﴾

(and Allah is Muhit (encompassing and thoroughly comprehending) all that they do.) He knows how and what they came for, and this is why He made them taste the worst punishment. Ibn `Abbas, Mujahid, Qatadah, Ad-Dahhak and As-Suddi commented on Allah's statement,

﴿وَلاَ تَكُونُواْ كَالَّذِينَ خَرَجُواْ مِن دِيَـرِهِم بَطَراً وَرِئَآءَ النَّاسِ﴾

(And be not like those who come out of their homes boastfully and to be seen of men,) "They were the idolators who fought against the Messenger of Allah at Badr.'' Muhammad bin Ka`b said, "When the Quraysh left Makkah towards Badr, they brought female singers and drums along. Allah revealed this verse,

﴿وَلاَ تَكُونُواْ كَالَّذِينَ خَرَجُواْ مِن دِيَـرِهِم بَطَراً وَرِئَآءَ النَّاسِ وَيَصُدُّونَ عَن سَبِيلِ اللَّهِ وَاللَّهُ بِمَا يَعْمَلُونَ مُحِيطٌ ﴾

(And be not like those who come out of their homes boastfully and to be seen of men, and hinder (men) from the path of Allah; and Allah is Muhit (encompassing and thoroughly comprehending) all that they do.)