Because of a lack of water to drink. Less than two months after entering into a divine covenant and agreeing to do “all the words that Jehovah [had] spoken, ” they violated his law on idolatry.
(‏ خر ١٧ :‏ ​ ٨ -‏ ١٦‏ )‏ هذَا وَارِدٌ ،‏ وَلكِنْ مَهْمَا كَانَ ٱلسَّبَبُ ،‏ « أَبَى [ٱلْإِسْرَائِيلِيُّونَ] أَنْ يَكُونُوا طَائِعِينَ » .‏