Where was this insight originally brought down from?
י = יצחק, יעקב
ש = שרה
ר = רבקה, רחל
א = אברהם
ל = לאה
The earliest work I could find was
But I'm not sure if it was originally thought by this Great Rabbi [השל"ה הקדוש] (earliest work I could find with it mentioned) or was it brought down originally from somewhere else. I find this insight to just be too good to be overlooked and then discovered till 16 or 17th century although it is possible this Great Rabbi did indeed originally discover it. It was mentioned in other sources as well without a reference which is why I am also further questioning it. The Midrash Rabbah has numerous acronyms but I have searched there and not found this one in there.