﴿ قَالَا رَبَّنَآ إِنَّنَا نَخَافُ أَن يَفْرُطَ عَلَيْنَآ أَوْ أَن يَطْغَىٰ ﴾

“The two [brothers] said: "O our Sustainer! Verily, we fear lest he act hastily with regard to us, or lest he [continue to] transgress all bounds of equity."”

Please check ayah 20:48 for complete tafsir.