It is narrated from Mu’adh bin Anas, from his father, who said: The Messenger of Allah (peace and blessings be upon him) said: “Whoever, when wearing new clothes, says: «اَلْحَمْدُ لِلّٰهِ الَّذِيْ كَسَانِيْ هٰذَا وَرَزَقَنِيْهٖ مِنْ غَيْرِ حَوْلٍ مِنِّىْ وَلَا قُوَّةٍ», his past sins will be forgiven.”
(Translation) All praise is due to Allah alone, Who has clothed me with this garment and granted it to me without any power or strength from myself.