Saying "Khuda Hafiz" when ending a conversation or bidding farewell.
It is permissible to say "Khuda Hafiz" when bidding farewell to someone or when ending a phone conversation, but the Sunnah and preferred method is to say "Assalamu Alaikum" or "Astawdi'ullaha deenaka" or to recite the supplications that are narrated from the Prophet (peace be upon him). (Aham Masail/Vol:1/Page:136)