It is narrated on the authority of Abu Saeed al-Khudree (may Allah be pleased with him) who said that when the Messenger of Allah sallallahu ‘alayhi wa salam used to wear new clothing, he would name it by its name either qamees (shirt) or ‘imaamah (turban) then say: “
اللّهُـمَّ لَـكَ الحَـمْـدُ أنْـتَ كَسَـوْتَنيهِ، أََسْأََلُـكَ مِـنْ خَـيرِهِ وَخَـيْرِ مَا صُنِعَ لَـه، وَأَعوذُ بِكَ مِـنْ شَـرِّهِ وَشَـرِّ مـا صُنِعَ لَـهُ
O Allah for you is praise! You clothed me it and I ask you for its good and the for what it was made for. And I seek refuge in you from its evil and the evil of what it has been created for” [Abu Dawood: 4020 , Al Nasaee, Tirmidhi,Hakim, Ahmad and others]
It is the sunnah of our beloved Prophet(SAW) to recite dua before wearing new clothes. May Allah(Azzawajjal) guide us to follow the sunnah of His beloved Messenger(SAW).