Psalms 21:1-13
1 The king shall joy in thy strength, O LORD; and in thy salvation how greatly shall he rejoice!
2 Thou hast given him his heart's desire, and hast not withholden the request of his lips. Selah.
3 For thou preventest him with the blessings of goodness: thou settest a crown of pure gold on his head.
4 He asked life of thee, and thou gavest it him, even length of days for ever and ever.
5 His glory is great in thy salvation: honour and majesty hast thou laid upon him.
6 For thou hast made him most blessed for ever: thou hast made him exceeding glad with thy countenance.
7 For the king trusteth in the LORD, and through the mercy of the most High he shall not be moved.
8 Thine hand shall find out all thine enemies: thy right hand shall find out those that hate thee.
9 Thou shalt make them as a fiery oven in the time of thine anger: the LORD shall swallow them up in his wrath, and the fire shall devour them.
10 Their fruit shalt thou destroy from the earth, and their seed from among the children of men.
11 For they intended evil against thee: they imagined a mischievous device, which they are not able to perform.
12 Therefore shalt thou make them turn their back, when thou shalt make ready thine arrows upon thy strings against the face of them.
13 Be thou exalted, LORD, in thine own strength: so will we sing and praise thy power.
Again, to the chief musician, the psalm of David.
The king shall joy in thy strength, O LORD; and in thy salvation how greatly shall he rejoice! Thou hast given him his heart's desire, and you have not withheld the requests of his lips (Psalms 21:1-2).
Now the Selah indicates, really, sort of a change of thought. It sort of introduces a new idea. It is just sort of a rest, and then introducing of a new idea, new thought pattern.
For you prevent him with the blessings of goodness: you set a crown of pure gold on his head. He asks for life from thee, and you gave it to him, even the length of days for ever and ever. His glory is great in thy salvation (Psalms 21:3-5):
He is talking about the king's delight in the Lord, and how he was just so gracious for what God has done.
For thou hast made him most blessed for ever: thou hast made him exceeding glad with thy countenance. For the king trusts in the LORD, and through the mercy of the Most High he shall not be moved. Your hand shall find out all your enemies: your right hand shall find out those that hate thee. You will make them as a fiery oven in the time of thine anger: the LORD will swallow them up in his wrath, and the fire shall devour them. Their fruit will you destroy from the earth, and their seed from among the children of men. For they intended evil against thee: they imagined mischievous devices, that they are not able to perform. Therefore thou shalt make them to turn their back, when thou shalt make ready your arrows upon thy strings against the face of them. Be thou exalted, LORD, in your own strength: so will we sing of thy praise and thy power (Psalms 21:5-13). "