Luke 1:42 And she spake out with a loud voice, and said, Blessed [art] thou among women, and blessed [is] the fruit of thy womb.
(Of course, you have no scriptural support for even Gabriel praying to saints, do you?)
No, but I have scriptural support for Gabriel honoring Mary and saying to her "Hail, Full of Grace". And Mary is not dead. She's alive to God. We are still connected to the entire Body of Christ, past, present and future. Mary and the other saints can pray for us just as surely as you can pray for me.
Luke 1:41-42...And it came to pass that, when Elizabeth heard the salutation of Mary, the babe leapt in her womb, and Elizabeth was filled with The Holy Ghost; and she spake out a loud voice, and said, Blessed art thou among women, and blessed is the fruit of thy womb.