Targum Pseudo-Jonathan on Exodus (Exodus 24:7) records the moment the covenant was sealed: Mosheh took the Book of the Covenant of the Law and read before the people; and they said, All the words which the Lord hath spoken we will perform and obey.
Na'aseh v'Nishmah — The Inverted Order
The Hebrew is na'aseh v'nishmah — we will perform and obey, or more literally, we will do and we will hear. Note the order. Doing first. Hearing second. The action precedes the understanding.
The Babylonian Talmud (Shabbat 88a) records a tradition that when Israel said these two words in this order, a heavenly voice proclaimed: Who revealed this secret to My children? It is a secret used by the ministering angels. In other words, Israel discovered, at Sinai, what angels already knew — that willing service precedes comprehension, that trust acts before it analyzes.
The Book of the Covenant
The Torah names the document Moses reads: Sefer HaBrit, the Book of the Covenant. Most scholars identify this as the laws recorded in Exodus 20-23 — the Ten Commandments and the Mishpatim that followed. Moses has just written them down (Exodus 24:4), and now he reads them aloud to the assembled people.
This is arguably the first public Torah reading in Jewish history. Every weekly parashah reading in synagogues, every Simchat Torah dance, every aliyah called up to the bima — all of it traces back to this moment at the foot of the mountain.
The Takeaway
Some commitments cannot wait for full understanding. The Torah was accepted by a people willing to do first and understand later — and that willingness is the hinge on which every covenant since has turned.