A dua book quoted that there is a hadeeth in Sahih Muslim wherein Rasulullah (salallahu aleyhi was salaam) said: Whoever takes the Quran with the intention of reciting it, and recites this dua before it...''.............'' Allah wil give him 50 000 hasana for each letter. The dua is; Allahumma bil hakki anzaltahu wa bil hakki nazal. Allahumma azzim raghbati fihi wadjalhu nuran libasari. Wa shifa'an lisadri. Allahumma zayyin bihi lisani wadjam'il bihi wadjhi wa kawwi bihi djasadi. Wazukni tilawatahu ala taatika ana al'layli wa atrafan'nahar. Wahshurni ma'an nabiyyi Muhammadin (salallahu aleyhi was salaam) wa alihil ahyar. Is this correct and saheeh, please give me the excact source in Muslim (bookname & hadeeth number) Was salaam

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.

The supplication which you mentioned is not a narration from the Prophet and it is not reported by Imaam Muslim and we have not come across it in any books of Sunnah.

Allaah Knows best.