John Gill Commentary Psalms 139:8

"If I ascend up into heaven, thou art there: If I make my bed in Sheol, behold, thou art there." — Psalms 139:8 (ASV)

If I ascend up into heaven, you [are] there
No man has ascended or can ascend to heaven of himself; it is an hyperbolical expression, as are those that follow; none but Christ has ascended to heaven by his own power, who descended from it; saints hope to go there at death, and, when they do, they find God there; that is his habitation, his throne is there, yea, that is his throne; here he keeps court and has his attendants, and here he will be seen and enjoyed by his people to all eternity;

if I make my bed in hell, behold, you [are there] ;
which, if understood of the place of the damned, is a place of torment, and a very unfit one to make a bed in, being a lake burning with fire and brimstone; and where the smoke of their torment ascends for ever, and they have no rest day or night; their worm never dies, and their fire is not quenched; and even here God is: hell is not only naked before him, and all its inhabitants in his view; but he is here in his powerful presence, keeping the devils in chains of darkness; turning wicked men daily into it, pouring out his wrath upon them, placing and continuing an unpassable gulf between them and happy souls: though rather this is to be understood of the grave, in which sense the word is often used; and so Kimchi, Aben Ezra, and Arama, interpret it of the lowest parts of the earth, as opposed to heaven; the grave is a bed to the saints, where they lie down and rest, and sleep till the resurrection morn, (Job 14:12) (Job 17:13Job 17:16) (Isaiah 57:2) ; and here the Lord is watching over and keeping their dust, and will raise it up again at the last day.

``there is your Word.''