تُبْلَی وَيُخْلِفُ اللَّهُ تَعَالَی

Tubla- wa yukhliful-laahu ta'aalaa

May you wear it out and Allah (Ta'aala) replace it [with another]. The Companions used to make this dua when they saw someone wearing new clothes.

Reference: Sahih (Albani). Abu Dawud: 4020