What is the ruling on saying "Ma'a as-salamah" (Go with peace/Goodbye) at the end of a call?

There is no harm in the phrase "in God's care and keeping," but it is preferable and better to use established phrases such as "Assalamu Alaikum" (Peace be upon you) or "Astoudi'ukumullah" (I entrust you to God), following the example of the Prophet, peace and blessings be upon him, who used to greet upon entering a gathering and bid farewell upon leaving it.