Esias 7:4

4 And thou shalt say to him, Take care to be quiet, and fear not, neither let thy soul be disheartened because of these two smoking firebrands: for when my fierce anger is over, I will heal again.

Esias 7:4 In-Context

2 And a message was brought to the house of David, saying, Aram has conspired with Ephraim. And his soul was amazed, and the soul of his people, as in a wood a tree is moved by the wind.
3 And the Lord said to Esaias, Go forth to meet Achaz, thou, and thy son Jasub who is left, to the pool of the upper way of the fuller's field.
4 And thou shalt say to him, Take care to be quiet, and fear not, neither let thy soul be disheartened because of these two smoking firebrands: for when my fierce anger is over, I will heal again.
5 And the son of Aram, and the son of Romelias, forasmuch as they have devised an evil counsel, ,
6 We will go up against Judea, and having conferred with them we will turn them away to our side, and we will make the son of Tabeel king of it;

The Brenton translation of the Septuagint is in the public domain.