اللَّهُمَّ لَكَ الْحَمْدُ كَمَا كَسَوْتَنِيهِ أَسْأَلُكَ خَيْرَهُ وَخَيْرَ مَا صُنِعَ لَهُ وَأَعُوذُ مِنْ شَرِّهِ وَشَرِّ مَا صُنِعَ لَهُ

"O Allah, all praise is to You, just as You have dressed me, I seek Your blessings of it and the blessings of what it is made of and I seek protection and Your refuge from all evil and the evil of that which it is made of". (Mishkat)

Umar (R.A.) stated that Prophet Mohammad (SAW.) said that if a person recites the following dua when dressing in new clothing and gives the old clothing in charity, then Allah will protect him both in this life and the Aakhirah and he will be under Allah's cover (i.e. he will be protected from all calamities and his sins will be hidden). (Mishkat)