Dua to be Recited When Entering a Marketplace:
لَاإِلهَ إلاَّ اللهُ وَحْدَهُ لَا شَرِيْكَ لَهُ لَهُ الْمُلْكُ وَ لَهُ الْحَمْدُ يُحْيِيْ وَيُمِيْتُ وَهُوَ حَيٌّ لَا يَمُوْتُ بِيَدِهِ الْخَيْرُ وَهُوَ عَلىَ كُلِّ شَيْئٍ قَدِيْر

"There is no deity except Allah, the One and Only; He has no partner. To Him belongs sovereignty, and to Him belongs all praise. He gives life and causes death, and He is eternally-living and does not die. In His hand is all good, and He has power over all things."

Fazeelat:
Whoever recites these words upon entering the marketplace will be rewarded with one million good deeds, one million of their sins will be forgiven, and their status will be elevated one million times.
(Tirmidhi, Hadith no. 3428)