I think this:

"این نیز بگذرد"

Attributed to Attar of Nishapur (1142-1221), who was beheaded by Genghis Kahn's Mongols. In one of Attar's fables, a powerful king gathered a group of wise men and asked them to produce a ring that would make him happy when sad, and sad when happy. After much consultation among themselves, the wise men presented the king with a ring inscribed "This, too, will pass".

- https://archive.org/details/quoteverifierwho00keye/page/160/...

We live now in bad days. This, too, will pass.