Al-Anbiyaa • BN-TAFSEER-IBN-E-KASEER
﴿ قَالُوٓا۟ أَجِئْتَنَا بِٱلْحَقِّ أَمْ أَنتَ مِنَ ٱللَّٰعِبِينَ ﴾
“They asked: “Hast thou come unto us [with this claim] in all earnest - or art thou one of those jesters?””
Please check ayah 21:56 for complete tafsir.