After each obligatory prayer, you may say this authentic remembrance:
“La ilaha illallahu wahdahu la sharika lah, lahul-mulku wa lahul-hamd, wa huwa ‘ala kulli shay’in qadir. Allahumma la mani‘a lima a‘tayt, wa la mu‘tiya lima mana‘t, wa la yanfa‘u dhal-jaddi minkal-jadd.”
Meaning: “There is no god but Allah alone, without partner. To Him belongs the kingdom and all praise, and He has power over everything. O Allah, none can withhold what You give, none can give what You withhold, and wealth or status cannot benefit anyone against You.” This was reported as a remembrance the Prophet ﷺ said after every obligatory prayer (Sahih Bukhari, Hadith 844).
You can also make personal dua after completing your prayer. The specific wording above is recommended, not an obligation.
