Shankaracharya defeated all his opponents, but one gave him some trouble. The name of this opponent was Bandanashastri and his wife's name was Bharatishastri.
Shankaracharya and Bandanashastri needed a judge for their debate. Bharatishastri, like her husband, was conversant with Vedic literature. So Bandanashastri said, "She will be by far the best judge," and Shankaracharya fully agreed.
The debate commenced and it took Shankaracharya three days to defeat Bandanashastri. When Bandanashastri lost, his wife said to Shankaracharya, "Now you have to accept my challenge. I want to challenge you."
Then Shankaracharya said, "Oh, please give me six months' time." He took six months to prepare himself and then he said, "Now I am ready." The debate began and with greatest difficulty he defeated Bharatishastri.
Shankaracharya had a religious ashram and after this debate he named it after her. His pride was deeply hurt that it took him such a long time to defeat her.From:Sri Chinmoy,Transfiguration and other stories, Agni Press, 2007
Sourced from https://srichinmoylibrary.com/trn