If we compare Heb. 5:7 and Gethsemane's cry, I think the force of the Psalm will be evident. The answer in the Psalm is not being preserved from dying, but life as risen in glory above, made most blessed forever; not sparing life for a time here, but honor and great majesty laid upon Him as man in a higher and more glorious condition. Christ as a man, though mighty to do things, asked everything of His Father. Dependence was His perfection. At Lazarus' tomb He asked, knew His Father heard Him always; asked in John 12; asked that the cup might pass. Only the word αἰτέω is not used of Him. The necessity of an event does not hinder asking. Everything in God's purpose will be necessarily accomplished; but He leads men's hearts to ask, as the moral filling up of their relationship with Him. In Christ, as man, this was perfect.