It's beyond human control
From Homer's Illiad (8th century BC), although not all versions translate as "in the lap of the gods". For example this version by Samuel Butler (1898).
On this he [Aneas] cried out to the two Ajaxes and Menelaus, "Ajaxes
captains of the Argives, and Menelaus, give the dead body over to
them that are best able to defend it, and come to the rescue of
us living; for Hector and Aeneas who are the two best men among
the Trojans, are pressing us hard in the full tide of war.
Nevertheless the issue lies on the lap of heaven, I will
therefore hurl my spear and leave the rest to Jove."
Other variations from the 18th and 19th centuries include:
"But all these things rest upon the knees of the gods." - Theodore Alois Buckley (1873)
"Yet verily these issues lie in the lap of the gods." Andrew Lang, M.A., Walter Leaf, Litt.D., And Ernest Myers, M.A. (1891)
"Yet is the issue in the hands of Heav'n." - Edward Earl of Derby (1864)
"That lies in the laps of the gods." - Butcher and Lang (1909)