ذِكْرُ السَّبَبِ الَّذِي مِنْ أَجْلِهِ سُمَيَّ الْخَضِرُ خَضِرًا
that the Messenger of Allah ﷺ said: "He was called Al-Khadir because he sat on a barren Farwah and it turned green beneath him." (Using translation from Tirmidhī 3151)
قَالَ رَسُولُ اللَّهِ ﷺ «إِنَّمَا سُمَيَّ الْخَضِرُ خَضِرًا لِأَنَّهُ جَلَسَ عَلَى فَرْوَةٍ بَيْضَاءَ فَإِذَا هِيَ تَهْتَزُّ تَحْتَهُ خَضْرَاءَ»