Who claimed to be a prophet during the time of Hazrat Abu Bakr (R.A)? 

1. Musaylimah Kazzab
2. Aswad Ansi
3. Talha bin Khuwailid
4. Sajah bint Khuwailid

Musaylimah the Liar (d. 633 CE) led the Banu Hanifa tribe in Yamama (Najd), claiming prophethood with fabricated verses mimicking the Quran. He was defeated by Khalid ibn al-Walid (R.A.) at the Battle of Yamama (12 AH), where 1,200 Muslims including Salim Mawla Abi Hudhayfa (R.A.) died. This battle prompted Quranic compilation. Other false prophets included Tulayha and Sajah, but Musaylimah was the most dangerous.