מדרש אויף רות 3:12

"And now, though it is true that I maybe a redeemer" (Ruth 3:12) is written, its reason being that Bo'az, knowing there is another redeemer closer than him, therefore said "that I may be a redeemer" — "may" being the language of doubt — maybe he will redeem — good! — or maybe he will not redeem. And he was not certain that he would redeem, for he said "If he does not desire to redeem you, then I myself will redeem you." Thus "that I may be a redeemer" is written, "that I be a redeemer" is read.