pour oil on troubled waters

pour oil on the (troubled) waters AND pour oil on troubled waters (to try to make people feel better and become friendly again after an argument) — действовать успокаивающе; умиротворять; ~ зубы заговаривать (контекст.)

Example 1: "Well, I suppose," Jack put in easily, "we're all as good as we can be in one way or another." Good man, Jack, she thought, always the one to pour oil on troubled waters. (Alice Taylor, "The Woman of the House", 1997)

Example 2: She patiently poured oil on Capote's roiled waters. (TIME, 2006)

Example 3: "Silvia's not here. I've been told she's gone into the village. If she's gone to see that brother of yours, I swear I'll break her neck!" He looked as though he might. Sparks flew from his eyes that were suddenly as black and threatening as thunder. "I can meet her when she gets back." Ronni smiled a light smile, seeking to pour oil on troubled waters. "Please don't worry on my account. It doesn't matter." "It does matter. I told her to be here! She had no business going off!" "Maybe she got tired of waiting. After all, I was late." (Stephanie Howard, "Conspiracy of love")

Related vocabulary:
[patch it up]
[sink one's differences]
[build bridges]
[mend fences]
[bury the hatchet]
[olive branch]
[что было — то было]
let bygones be bygones
[кто старое помянет, тому глаз вон]
[быльём поросло]
Let the dead bury their dead.