In the Babylonian Talmud, tractate Shabbat 88b, the Sage Yehoshua Ben Levi explains that when Hashem uttered the first words of the Dibraya, all the people at Sinai died. That is, the Neshama of all of Israel, at Sinai, left their bodies. He derives this from Shir HaShirim (Song of Songs) 5:6, which states “My Nefesh departed when He spoke.”
The idea is elucidated further in Midrash Rabah. The voice of Hashem was so awesome that the children of Israel could not withstand it. And so, when Hashem spoke and said “I Am the Lord” (Exodus 20:2), the Neshama of every person at Sinai left. This is what Shlomo was alluding to in Shir HaShirim.
However, the Holy One, Blessed Be He, made us a nation at Sinai. He made us a nation in order to give us Torah so that we would be a light unto the nations. It was not his intention to destroy us; rather it was his intention to edify us. Therefore, He continued, saying, “your G-d”. By saying “your G-d”, Hashem comforted his people. This allowed their Neshamot to return. In other words, at Sinai, the children of Israel died and were resurrected.
How were they resurrected? Yeshoshua Ben Levi tells us that the Holy One, Blessed Be He brought dew upon us. This dew allowed us to be raised from the dead both at Sinai and in the future. Resurrection, as an idea, has been understood in Judaism since ancient times. The resurrection of the dead is an event we look toward at the end of days. This is why in the Amidah all Israel prays, “Blessed are You, O L-rd, who raises the dead”.