At least six passages in Scripture highlight singing to God because He is the King.
Psalm 22:21 Save me from the lion’s mouth: for thou hast heard me from the horns of the unicorns.
Psalm 22:22 I will declare thy name unto my brethren: in the midst of the congregation will I praise thee.
Psalm 22:23 Ye that fear the LORD, praise him; all ye the seed of Jacob, glorify him; and fear him, all ye the seed of Israel.
Psalm 22:24 For he hath not despised nor abhorred the affliction of the afflicted; neither hath he hid his face from him; but when he cried unto him, he heard.
Psalm 22:25 My praise shall be of thee in the great congregation: I will pay my vows before them that fear him.
Psalm 22:26 The meek shall eat and be satisfied: they shall praise the LORD that seek him: your heart shall live for ever.
Psalm 22:27 All the ends of the world shall remember and turn unto the LORD: and all the kindreds of the nations shall worship before thee.
Psalm 22:28 For the kingdom is the LORD’S: and he is the governor among the nations.
Psalm 47:1 <To the chief Musician, A Psalm for the sons of Korah.> O clap your hands, all ye people; shout unto God with the voice of triumph.
Psalm 47:2 For the LORD most high is terrible; he is a great King over all the earth.
Psalm 47:3 He shall subdue the people under us, and the nations under our feet.
Psalm 47:4 He shall choose our inheritance for us, the excellency of Jacob whom he loved. Selah.
Psalm 47:5 God is gone up with a shout, the LORD with the sound of a trumpet.
Psalm 47:6 Sing praises to God, sing praises: sing praises unto our King, sing praises.
Psalm 47:7 For God is the King of all the earth: sing ye praises with understanding.
Psalm 47:8 God reigneth over the heathen: God sitteth upon the throne of his holiness.
Psalm 68:24 They have seen thy goings, O God; even the goings of my God, my King, in the sanctuary.
Psalm 68:25 The singers went before, the players on instruments followed after; among them were the damsels playing with timbrels.
Psalm 68:26 Bless ye God in the congregations, even the Lord, from the fountain of Israel.
Psalm 95:1 O come, let us sing unto the LORD: let us make a joyful noise to the rock of our salvation.
Psalm 95:2 Let us come before his presence with thanksgiving, and make a joyful noise unto him with psalms.
Psalm 95:3 For the LORD is a great God, and a great King above all gods.
Psalm 98:1 <A Psalm.> O sing unto the LORD a new song; for he hath done marvellous things: his right hand, and his holy arm, hath gotten him the victory.
Psalm 98:2 The LORD hath made known his salvation: his righteousness hath he openly shewed in the sight of the heathen.
Psalm 98:3 He hath remembered his mercy and his truth toward the house of Israel: all the ends of the earth have seen the salvation of our God.
Psalm 98:4 Make a joyful noise unto the LORD, all the earth: make a loud noise, and rejoice, and sing praise.
Psalm 98:5 Sing unto the LORD with the harp; with the harp, and the voice of a psalm.
Psalm 98:6 With trumpets and sound of cornet make a joyful noise before the LORD, the King.
Revelation 15:1 And I saw another sign in heaven, great and marvellous, seven angels having the seven last plagues; for in them is filled up the wrath of God.
Revelation 15:2 And I saw as it were a sea of glass mingled with fire: and them that had gotten the victory over the beast, and over his image, and over his mark, and over the number of his name, stand on the sea of glass, having the harps of God.
Revelation 15:3 And they sing the song of Moses the servant of God, and the song of the Lamb, saying, Great and marvellous are thy works, Lord God Almighty; just and true are thy ways, thou King of saints.
Revelation 15:4 Who shall not fear thee, O Lord, and glorify thy name? for thou only art holy: for all nations shall come and worship before thee; for thy judgments are made manifest.
Only by meditating much on these passages will we as Christians fully have the right mindset about singing in worship of our God who is the great King!