C. F. Keil and Franz Delitzsch on 2 Kings 5:19

2Ki 5:19

Elisha answered, “Go in peace,” wishing the departing Syrian the peace of God upon the road, without thereby either approving or disapproving the religious conviction which he had expressed. For as Naaman had not asked permission to go with his king into the temple of Rimmon, but had simply said, might Jehovah forgive him or be indulgent with him in this matter, Elisha could do nothing more, without a special command from God, than commend the heathen, who had been brought to belief in the God of Israel as the true God by the miraculous cure of his leprosy, to the further guidance of the Lord and of His grace.Most of the earlier theologians found in Elisha’s words a direct approval of the religious conviction expressed by Naaman and his attitude towards idolatry; and since they could not admit that a prophet would have permitted a heathen alone to participate in idolatrous ceremonies, endeavoured to get rid of the consequence resulting from it, viz., licitam ergo esse Christianis συμφώνησιν πιστοῦ μετὰ ἀπιστοῦ, seu symbolizationem et communicationem cum ceremonia idololatrica, either by appealing to the use of השׁתּחות and to the distinction between incurvatio regis voluntaria et religiosa (real worship) and incurvatio servilis et coacta Naemani, quae erat politica et civilis (mere prostration from civil connivance), or by the ungrammatical explanation that Naaman merely spoke of what he had already done, not of what he would do in future (vid., Pfeiffer, Dub. vex. p. 445ff., and J. Meyer, ad Seder Olam, p. 904ff., Budd., and others). - Both are unsatisfactory. The dreaded consequence falls of itself if we only distinguish between the times of the old covenant and those of the new. Under the old covenant the time had not yet come in which the heathen, who came to the knowledge of the true deity of the God of Israel, could be required to break off from all their heathen ways, unless they would formally enter into fellowship with the covenant nation.