Acts 2:42
and they were constantly attending the teaching of the apostles and the fellowship, and the breaking of bread, and the prayers.
1 Corinthians 15:33-34
Be not deceived; evil companionships corrupt good morals.
2 Corinthians 6:14-18
Become not unequally yoked with unbelievers; for what fellowship have righteousness and lawlessness? And what communion has light with darkness?
Hebrews 10:24
and let us consider one another, to incite to love and good works;
Revelation 18:4
And I heard another voice out of Heaven saying, "Come forth out of her, my people, that ye have no fellowship with her sins, and that ye receive not of her plagues;