temper something with something
1. Fig. to harden something, such as metal, with something. You have to temper the metal pieces with very high heat. The sheet of metal was tempered by the application of great pressure.
2. Fig. to soften the impact of something, such as news, with something. We can temper this disaster story a bit with a picture of the happy survivors. The news story was tempered with a paragraph of explanation and justification.