Peter Pett's Commentary on the Bible
1 Kings 11:34
“ However that may be I will not take the whole kingdom out of his hand, but I will make him prince all the days of his life, for David my servant's sake whom I chose, who kept my commandments and my statutes,”
However, because of His promise to David His chosen king, and for David's sake, and because David had been obedient to His commandments and statutes, He would not take the whole kingdom away from Solomon. Indeed He would make him ‘prince/ruler' all the days of his life. There is here both a degrading and a consolidating of Solomon's position. While outwardly king over all Israel, it is no longer a permanent dynastic position, but one dependent on the will of the people and the mind of YHWH.
“ But I will take the kingdom out of his son's hand, and will give it to you, even ten tribes. And to his son will I give one tribe, that David my servant may have a lamp always before me in Jerusalem, the city which I have chosen for myself to put my name there.”
And while it was YHWH's intention to take the majority of the kingdom out of the hands of the house of Solomon, ‘even ten tribes' (ten regularly means ‘a good number'), He would not take the whole kingdom out of his son's hands. He would give him one tribe, in contrast to the ten tribes that He would give to Jeroboam. This clearly had to mean one tribe as well as Judah, in order to make up the twelve. Thus He saw Judah as already irrevocably belonging to David's house. (These two tribes would then be known as ‘Judah' (1 Kings 12:20) which became the accepted designation of the southern kingdom).
And the reason for this was so that David might always have a lamp before Him in Jerusalem, the city which YHWH ‘had chosen for Himself' in response to David's choice of it. Had David's house only ruled over Judah, Jerusalem, which was on the border between Judah and Benjamin, and partly belonged to each tribe, would have been in an impossible position. Thus in order to preserve it both Judah and Benjamin were required to unite as one kingdom.
The phrase, ‘that David my servant may have a lamp always before me in Jerusalem', the idea behind which is repeated in 1 Kings 15:4; 2 Kings 8:19, may possibly have in mind 2 Samuel 21:17 where David was seen as the lamp of Israel because as the chosen king he was seen as the nation's very life, and the means of God's light shining on them. It had been David's, and the people's, longing that his house might always be such a light, and God now confirms that it will be so. Compare how in Lamentations 4:20 the Davidic king was also seen as ‘the breath of our nostrils'. He was seen as essential to their whole wellbeing.
But in the end the lamp indicated a living representative of the house of David, just as the seven-branched lampstand in the Tabernacle visibly represented YHWH among His people. There would be a Davidic representative while the kingdom lasted.
Having ‘chosen Jerusalem' because it had been David's choice to make it His Sanctuary, God now confirmed His choice of Jerusalem as the place where His Name would dwell (compare 1 Kings 11:11 which was the first mention of such an idea concerning Jerusalem). We should note that this ‘choice' of Jerusalem is always linked with the name of David. It was the fact of the presence of the Davidic throne and of the Ark in Jerusalem that made Jerusalem YHWH's choice. (Thus once Jerusalem rejected Jesus it ceased to be the city of God's choice).