Psalm 1, yeah God's wisdom tells us we shouldn't be in companionship with unbelievers.
2 Corinthians 6:14
Eeh, Psalm 1 can be interpreted that way but it can also be interpreted as, "Don't walk in sin." instead of "Don't hang out with those who walk in sin."
Because honestly, if you are gonna further God's kingdom you are gonna have to at least acknowledge the unsaved and the people who don't walk with God.
I think I'll go ahead and paste Psalm 1 onto here
Psalm 1 New American Standard Bible (NASB)
BOOK 1
The Righteous and the Wicked Contrasted.
1 How blessed is the man who does not walk in the counsel of the wicked,
Nor stand in the path of sinners,
Nor sit in the seat of scoffers!
2 But his delight is in the law of the Lord,
And in His law he meditates day and night.
3 He will be like a tree
firmly planted by streams of water,
Which yields its fruit in its season
And its leaf does not wither;
And in whatever he does, he prospers.
4 The wicked are not so,
But they are like chaff which the wind drives away.
5 Therefore the wicked will not stand in the judgment,
Nor sinners in the assembly of the righteous.
6 For the Lord knows the way of the righteous,
But the way of the wicked will perish.