Sending durood upon Nabi (sallallahu alaihi wasallam)

Q: I have a friend and his mom asked him, as she is jahil, is it permissible to send darood on Nabi Muhammad (sallallahu alaihi wasallam) and he said I don't know with respect because he thought that it may be shirk and then he said"Lekin kiya zaroorat he" with respect not with niyyat of disrespect. He said this because he thought it means that we are maybe asking from Nabi Muhammad (sallallahu alaihi wasallam) or something. Is this kufr?