﴿ وَٱضْمُمْ يَدَكَ إِلَىٰ جَنَاحِكَ تَخْرُجْ بَيْضَآءَ مِنْ غَيْرِ سُوٓءٍ ءَايَةً أُخْرَىٰ ﴾

“"Now place thy hand within thy armpit: it will come forth [shining] white, without blemish, as another sign [of Our grace],”

Please check ayah 20:35 for complete tafsir.