Authentic Supplication Number 115.

The Prophet  said: “If you see one who sells, or buys in the Mosque then say: La ‘arbahallahu tijarataka (137) and if you see someone announcing his lost [thing] then say: La radda ‘allahu `alaiyka dhallataka (138).

Footnotes.
(137) May Allah not render your business profitable.
(138) May Allah not bring back your lost [thing].

Reporters.
‘Al-‘Adawee said it was comely and that it was reported by At-Tirmithi, #1321. At-Tirmithi said it was comely strange. ‘Al-‘Adawee also said that it was reported by Al-Darami, page 326 of volume 1; Ibn Jarood, #562; Al-Bayhaqi, #447/2, Al-Hakim, #56/2, who said it sound according to the conditions of Muslim; Ath-thahabi who agreed with Al-Hakim; and Ibn As-Sunni, #153, and #151. ‘Al-‘Albani said it was sound in his Saheeh Al-Jami`i As-Sagheeri wa Ziyadatihi, #573.