Deuteronomy 31:16
And the LORD said unto Moses, Behold, thou shalt sleep with thy fathers; and this people will rise up, and go a whoring after the gods of the strangers of the land, whither they go to be among them, and will forsake me, and break my covenant which I have made with them.
The Lord tells Moses that he is about to die and be numbered among his dead fathers, and foretells that after his death Israel will rise up and turn to the foreign gods of the land, forsake Him, and break His covenant. The thou that is to sleep is Moses himself as a whole living, intelligent being, and his sleep is real death as an unconscious lying down, not his body alone sleeping while a separate soul stays awake. In that sleep the dead rest without consciousness, knowledge, thought, memory, pain, or awareness of time and earthly troubles, like a weary traveler in deep dreamless slumber, rich and poor together hearing and knowing nothing until they are all awakened and judged together at the resurrection. It does not mean burial beside them, for Moses was buried apart in Moab, nor going to join their conscious spirits, nor passing into conscious life with Christ or into hell fire, but resting unconscious with the silent dead until God should raise him for a special purpose. Because Israel broke the conditions of the first covenant, that covenant ceased, and for their disobedience God would forsake them, hide His face, and withdraw His protection until they were devoured and consumed as a nation.
Death as Unconscious Sleep
The phrase sleep with thy fathers is a figure and name for death, meaning Moses will die and be gathered to his fathers. God speaks of death as a sleep, and sleep is used as a way to speak of death and as evidence that a person sleeps in death. The thou told to sleep is Moses himself as a whole man, the whole living, rational, intelligent, organized being, all that constituted the man, not his body alone while a separate inner soul flies off to higher conscious activity. His fathers with whom he would sleep are likewise whole persons sleeping, and the sleep is literal death and an unconscious lying down in an unconscious state, not a moral sleep. Because the same thou that is told death approaches is told of this sleep, thou keeps one meaning throughout, which proves the thou in the Eden threat cannot mean an immortal soul dying a moral death, since that would require Moses on Pisgah to suffer a moral sleep of the soul.
Sleep with thy fathers does not mean burial, since Moses was buried separately in Moab, nor joining the conscious spirits of ancestors. That latter view would require both the ancestors' spirits and Moses' spirit after death to be asleep, whereas the meaning is that Moses will die and be numbered among the silent dead. This sleep means the dead rest without consciousness, knowledge, thought, memory, pain, trouble, anxiety, or awareness of time and earthly events, and the dead do not know or see the troubles happening on earth. It is like a weary traveler in profound dreamless slumber who awakes where he fell asleep and resumes thinking where he left off. The dead remain in that blank, quiet rest, rich and poor together, hearing nothing and knowing nothing, until the heavens be no more, when all are awakened, judged, and rewarded together at the resurrection, with no reward or punishment before judgment.
The verse uses sleep as a figure for death, not as a transition to conscious life elsewhere, for Moses would rest with his ancestors unconscious in death until God raised him for a special purpose. Dying is called sleeping with fathers to show the dead sleep in the grave and are not with Christ in heaven nor in hell fire. To sleep with the fathers means to die, with sleep used as a name for death in the same way Jesus speaks of Lazarus as asleep.
Foretold Covenant Breaking
The Lord told Moses beforehand that after his death this people would rise up and go whoring after the gods of the strangers of the land, turning to the gods of the nations among whom they would live, and would forsake Him and break the covenant He had made with them. As Moses warned and predicted, that first covenant was broken and ceased because its conditions were not kept. Because of that disobedience to God's law, He would forsake them and hide His face from them and withdraw His protection until they were devoured and consumed as a nation. Their continued possession of Canaan depended on obedience to His commandments, so disobedience brought loss of His protection and failure of His purpose for them as a nation.
The verse stands in a chapter containing precepts, solemn injunctions, and blessed promises, together with Moses' final charge to the priests and to Joshua.