I need you now, are you going to come?
He hadn't prayed for Spock's return, or anything like it, back before V'ger, before Khan - before Kruge, even. He'd counted himself lucky, being able to wash his hands of it. A fellow officer was a fellow officer, and he didn't need to put time in trying to convert, or then again to controvert, the loyalty of a friend who just didn't seem to want it that way.
But that was life, and the road not taken. This was death. Much less of a decision. Much more of a loyalty.
So Bones held onto those damned black robes for dear life.