Rabbi Akiva was teaching Torah and his students were falling asleep, so he roused them by explaining that Queen Esther merited to rule over 127 Countries in the Schuss of her great-grandmother Sara, who lived for 127 years.

Sources

Parshas Chayei Sara Perek 23 Pessukim 1 and 2

Midrash Rabba Bereishis Parsha 58 Perek 3, Parsha 45 Perakim 4 and 5.

Parshas Lech Lecha Perek 16, Pessukim 1 - 11

Rashi on Possuk 1, 4 and 11

Midrash Rabba Esther Parsha 8 Perek 7

Baal Haturim on Second Possuk in Chayei Sara