﴿ بَلْ هُمُ ٱلْيَوْمَ مُسْتَسْلِمُونَ ﴾

“Nay, but on that Day they would willingly surrender [to God];”

(Nay, but this day) which is the Day of Judgement (they make full submission) the worshipper and the worshipped submitted to Allah and knew that the Truth is with Allah.