Deuteronomy 1:18

And at that time I taught you all the Ten Words which you are to practise about judgments of money, and judgments of life.

which you must practice i.e., the statutes and laws which were taught to them.

AND I COMMANDED YOU AT THAT TIME ALL THE THINGS WHICH YE SHOULD DO. “These are the ten differences between monetary and capital cases.” This is Rashi’s language quoting the Sifre. 18. See Sanhedrin 32a for these ten distinctions between monetary and capital cases. And if so, Moses is speaking here to the judges [previously] mentioned, and he abridged on the ten differences [by not enumerating them], for they are all deduced from verses.
And in line with the plain meaning of Scripture, the reference here is to the statutes and laws, the way wherein they must walk, and the deeds they must perform, for he [Moses] personally commanded, warned, and taught Israel all these matters. And the reason for mentioning this [subject] here is because it is known that this was the substance of Jethro’s counsel when he told Moses, Be thou for the people before G-d,, Verse 19. meaning that he was to pray in their behalf in the time of their affliction, and he further told him, And thou shalt teach them the statutes and the laws etc., meaning that he, himself, was to teach them the Torah. But regarding the execution of the law, Jethro advised him to appoint judges to assist him, and I have already explained it there. Therefore, Moses related here that when he designated the officers over thousands and hundreds he delegated them only over the execution of justice. He, however, would personally teach them [the people] everything they were to do in accordance with the Torah, because he hearkened to his father-in-law’s counsel and did all that he had said., Verse 24. Now Moses did not mention Jethro’s advice here, nor did he attribute to him anything that Jethro proposed. It appears to me that Moses did not want to mention it [the fact that he was following his father-in-law’s advice] in the presence of all Israel because of his humility, or it may be that it would not be to his honor to mention to that generation that he had married a Cushite woman. It is also possible that the reason [for not mentioning Jethro’s name] was because he had consulted the Divine Glory and this matter was done at the command of the Almighty. 2: “And Moses hearkened to the voice of his father-in-law and did all that ‘amar’ (he, [i.e. G-d] had said” Exodus 18:24). The Mechilta thus explains the word amar as referring to G-d, and not to Jethro.