صحيح البخاري

Narrated Warrad:

(the clerk of Al-Mughira bin Shu`ba) Once Al-Mughira dictated to me in a letter addressed to Muawiya that the Prophet (ﷺ) used to say after every compulsory prayer, "La ilaha illa l-lahu wahdahu la sharika lahu, lahu l-mulku wa lahu l-hamdu, wa huwa `ala kulli shay'in qadir. Allahumma la mani`a lima a`taita, wa la mu`tiya lima mana`ta, wa la yanfa`u dhal-jaddi minka l-jadd. [There is no Deity but Allah, Alone, no Partner to Him. His is the Kingdom and all praise, and Omnipotent is he. O Allah! Nobody can hold back what you gave, nobody can give what You held back, and no struggler's effort can benefit against You]." And Al-Hasan said, "Al-jadd' means prosperity [??]."