The Bible asks this question, “Does a spring pour forth from the same opening both fresh and salt water?” (Jas. 3:11). It’s not possible, is it? It’s either one or the other, but not both. Then, to drive the point home, Scripture asks this question, “Can a fig tree, my brethren, bear olives, or a grapevine bear figs?” (3:12). Again, that’s not possible. A tree only bears its own fruit.
James was not writing an essay about aquatic or gardening tips. He was illustrating the need for Christians to learn to control their tongue and 
emphasizing that it was not designed for two conflicting uses. “With it we bless our God and Father, and with it we curse men, who have been made in the similitude of God. Out of the same mouth proceed blessing and cursing. My brethren, these things ought not to be so” (3:9-10).
What comes out of your mouth? A Christian mouth is to “pour forth” blessing, not cursing. Is that hard? Certainly! But, “I can do all things through Christ who strengthens me” (Phil. 4:13).