After this he became not only a most faithful and diligent minister of the gospel, but also a staunch presbyterian, and had a very active hand in carrying on the covenanted work of reformation, from the year 1638, to the day of his death, and was among the very first who got a charge of horning from the bishop of St. Andrews, for refusing to buy and use the service-book, and book of canons then imposed by the king upon the church; which occasioned him and some others to give in several petitions and complaints to the council, both craving some mitigation therein, and shewing the sinfulness thereof, for which and some other considerations and overtures for relief, (mostly compiled by Mr. Henderson) they were by order of proclamation charged, within twenty-four hours, to leave the town of Edinburgh under the pain of rebellion. Again in the year 1638, when the national confession or covenant was agreed upon and sworn unto by almost all ranks in the land, the marquis of Hamilton being sent by the king to suppress the covenanters, who having held several conferences with him to little or no purpose, at last, he told them that the book of canons and liturgy should be discharged, on condition they should yield up their covenants, which proposition did not only displease them, but also made them more vigilant to support and vindicate that solemn deed. Whereupon Mr. Henderson was again set to work, and in a short time savoured the public with sufficient grounds and reasons why they could not recede from any part of that covenant. Some time after this, the table (so called) which was erected at Edinburgh for carrying on the reformation, being sorry that the town and shire of Aberdeen, (excited by the persuasion of their doctors) stood out and opposed the covenant and work of reformation, sent some earls with Messrs. Henderson, Dickson and Cant, to deal with them once more, and to see if they could reclaim that town and country.----But upon their arrival there, they could have no access to preach in any church; whereupon the three ministers resolved to preach in the earl of Marshal's close and hall as the weather favoured them. Accordingly they preached by turns, Mr. Dickson preached in the morning to a very numerous multitude, at noon Mr. Cant preached, and Mr. Henderson preached at night to no less an auditory than in the morning; and all of them pressed and produced arguments for subscribing the covenant; which had such effect upon the people, that, after public worship was over, about 500 persons subscribed the covenant, at one table there, of whom severals were people of the best quality in that place.[61]