Commentary for Berakhot 13:36

ותני רב יוסף למעלה מששים רבוא אתיא רביה רביה כתיב הכא רבו למעלה וכתיב התם (שמות א, ז) ובני ישראל פרו וישרצו וירבו:

On this Rab Joseph taught : They were upwards of [lema'alah] sixty myriads. One draws an analogy from the occurrence of the word rabah "many" in the following passages : here it is written, "they were very many," and elsewhere it is written, "And the children of Israel were fruitful, and increased abundantly, and became very many" (Exod. i. 7).

Abraham Cohen Footnotes to the English Translation of Masechet Berakhot