The first mitzvah is that we are commanded to acquire knowledge1 of the nature of G‑d's existence, i.e. to understand that He is the Original cause and Source of existence Who brings all creations into being.

The source of this commandment is G‑d's statement2 (exalted be He), "I am G‑d your Lord."

[We see that this commandment is included in the total of 613 from] the end of the tractate Makkos,3 which states, "613 commandments were given to Moshe at Sinai. From which verse do we see this? — 'The Torah which was commanded to us by Moshe.' "4 This indicates [that the number of mitzvos which Moshe commanded us equals] the numerical value of the word Torah.5 The Gemara than asks, "But is this the proper numerical value? It only totals 611!" The answer was given, "The two commandments 'I am G‑d your Lord' and 'Do not have any other gods'6 were heard from G‑d directly" [and not through Moshe. They are therefore not alluded to in the word Torah in this verse, which refers only to those 611 mitzvos which were given through Moshe. It is included, however, in the total of 613.]

It is clear from this passage that "I am G‑d your Lord," i.e. knowledge of G‑d, as explained above, is counted as one of the 613 mitzvos.