Lost Surahs Of The Quran & Codex Of Ibn-e-Masud (rta)
Usually “ Al-Khal ‘” and “ Al-Hafd ” are reported with reference to Ubay bin Kaab (rta) and if you read their translations then it become apparent that these were supplications of Ubay bin Kaab (rta) which he may have learnt from the Prophet (sws) but were wrongly attributed to Quran by some narrator. If these non-Quranic prayers were part of his mushaf, then his mushaf/notebook contained statements other than Quran and was meant for his own use, not as an official copy of the Quran.