Reference for Isaiah 38:21

וַיֹּ֣אמֶר יְשַׁעְיָ֔הוּ יִשְׂא֖וּ דְּבֶ֣לֶת תְּאֵנִ֑ים וְיִמְרְח֥וּ עַֽל־הַשְּׁחִ֖ין וְיֶֽחִי׃

And Isaiah said: ‘Let them take a cake of figs, and lay it for a plaster upon the boil, and he shall recover.’