If the Masbooq joined just as the Imaam said the Word 'As Salaam'

Q: Salaah-95: The Imaam had just said "As Salaam" and had not yet added "Alaykum" when a person joined the Jamaa'ah. Will he be considered as part of the Jamaa'ah?

Answer: He will not be part of the Jamaa'ah in the stated case and will have to repeat the Takbeer and start his own salaah. And Allaah knows best what is most correct.

Fatawa Rahimiyyah vol.2