The people; or, his people. So it is only a defect of the pronoun his, which is very frequent, and easily understood out of the foregoing word, the Lord. The sense is, when God, the Maker and Governor of this city, shall take a survey of all his citizens and subjects. It is an allusion to princes or governors of cities that use to write and keep a register of all their people. Hence holy then and true Israelites are said to be written among the living in Jerusalem, Isaiah 4:3; or, in the writing of the house of Israel, Ezekiel 13:9.
Related Commentaries of Psalms 87:6
Psalms 87:6
6 The LORD shall count, when he writeth up the people, that this man was born there. Selah.