1. have an ax to grind
如：She always has an ax to grind. You should take whatever she says with a pinch of salt.
2.not have one’s heart in the right place
如：He doesn’t have his heart in the right place. He would find every opportunity to stab in the back of others.
3. stab in the back
如：I was taken aback and didn’t think Zhang would stab me in the back. I placed too much trust in her.
4. badmouth somebody
如：I’ve never badmouthed anyone.
如：I’m really bored with his sitting there doing nothing but beefing.
6.speak with one’s tongue in one’s cheek
如：I feel sick of her. She always speaks with her tongue in her cheek.
7. smite with the tongue
如：Don't offend her. She always smites with the tongue.