Observe and hear all these words that I command you, in order that it may go well with you and with your children after you forever, when you do what is good and right in the eyes of Hashem your God.
English: “Observe and hear” — This teaches that if you observed a little, you will end up hearing much; and if you observed what you heard, you will end up observing even what you did not hear.
On the daf / in context: Observance of the known commandments leads to further understanding and even to the adoption of protective fences and stringencies.
Type of Learning
Derash on the verse (Sifrei) — the progressive nature of observance and learning.
What Is Learned
Observing a little leads to hearing much; observing what one has heard leads to observing even that which one has not yet heard (including protective measures).