C. F. Keil and Franz Delitzsch on 2 Kings 17:40-41

2Ki 17:40-41

They did not hearken, however (the subject is, of course, the ten tribes), but they (the descendants of the Israelites who remained in the land) do after their former manner. הראשׁון משׁפּטם is their manner of worshipping God, which was a mixture of idolatry and of the image-worship of Jehovah, as in 2Ki 17:34. - In 2Ki 17:41 this is repeated once more, and the whole of these reflections are brought to a close with the additional statement, that their children and grandchildren do the same to this day. - In the period following the Babylonian captivity the Samaritans relinquished actual idolatry, and by the adoption of the Mosaic book of the law were converted to monotheism. For the later history of the Samaritans, of whom a small handful have been preserved to the present day in the ancient Sichem, the present Nablus, see Theod. Guil. Joh. Juynboll, commentarii in historiam gentis Samaritanae, Lugd. Bat. 1846, 4, and H. Petermann, Samaria and the Samaritans, in Herzog’s Cycl.