Stephen Shoemaker has provided E. A. Budge's English translation of a Coptic text at
It is Pseudo-Cyril's Discourse on Mary Theotokos.
The prefacoty description states, "This text is one of the earliest Coptic traditions of Mary's Dormition, almost certainly from before the middle of the sixth century. It reflects much that is typical of the Coptic traditions of the Dormition, particularly in their earliest stages."
Via word-searches I found two uses of Mk. 16:15 --
"The Patriarch Cyril said unto the monk, 'Who sent thee about to teach these things?' And that monk said unto him, 'The Christ said, 'Go ye forth into all the world, and teach ye all the nations in My Name in every place.'" (A loose blend with Mt. 28:19)
And further along: "And she [Mary] said unto them, 'Hearken unto me, O ye whom God hath chosen to preach the Gospel throughout the world."
The author also mentions that he has read Josephus and Irenaeus.
Yours in Christ,
James Snapp, Jr.