"And it came to pass that after this manner of language did I persuade my brethren, that they might be faithful in keeping the commandments of God."
Laman and Lemuel probably still grumbled and complained, but I can imagine Sam supporting Nephi and wanting to do all he could to follow the will of the Lord.
Nephi mentions later that his is more skill in speech than that of his writing. To have the skills to speak and convince two rebellious brothers to doing something they don't want to is pretty amazing. By the added strength of the spirit behind the words Nephi was better able to pierce his brothers' hearts enough to have them obey, if not the spirit of the law, then the letter of the law.
Laman, Lemuel complain maybe still. But imagine Sam support Nephi same, want same do all can serve follow Lord His will, obey commandments from God.
Nephi say later his skill, where? Speak not write. Have skill speak persuade rebel brother+ do thing themself+ don't want amazing. Add strength from Spirit Nephi touch heart can. Help obey Commandment if not willing, then little force.