And as he was mighty in the public parts of religion, so he was a great practiser and encourager of the private duties thereof. Thus in the year 1640, when a charge was foisted in before the general assembly at the instance of Mr. Henry Guthrie minister at Stirling (afterward bishop of Dunkeld), against private society meetings (which were then abounding in the land), on which ensued much reasoning, the one side yielding that a paper before drawn up by Mr. Henderson should be agreed unto concerning the order to be kept in these meetings, &c. but Guthrie and his adherents opposing this, Mr. Rutherford, who was never much disposed to speak in judicatories, threw in this syllogism, "What the scriptures do warrant no assembly may discharge; but private meetings for religious exercises the scriptures do warrant, Mal. v. 16. _Then they that feared the Lord spake often one to another_, &c. James v. 16. _Confess your faults one to another, and pray one for another_, &c. These things could not be done in public meetings, &c." And although the earl of Seaforth there present, and those of Guthrie's faction upbraided this good man for this, yet it had influence upon the majority of the members, so that all the opposite party got done, was an act anent the ordering of family-worship. He was also one of the Scots commissioners appointed _anno_ 1643, to the Westminster assembly, and was very much beloved there for his unparalleled faithfulness and zeal in going about his Master's business. It was during this time that he published _lex rex_, and several other learned pieces against the Erastians, Anabaptists, Independents, and other sectaries that began to prevail and increase at that time, and none ever had the courage to take up the gauntlet of defiance thrown down by this champion[85]. When the principal business of this assembly was pretty well settled, Mr. Rutherford, on October 24, 1647, moved that it might be recorded in the scribe's book, that the assembly had enjoyed the assistance of the commissioners of the church of Scotland, all the time they had been debating and perfecting these four things mentioned in the solemn league, _viz._ Their composing a directory for worship, an uniform confession of faith, a form of church-government and discipline, and the public catechism, which was done in about a week after he and the rest returned home.