Albert Barnes Commentary Luke 10:39

"And she had a sister called Mary, who also sat at the Lord`s feet, and heard his word." — Luke 10:39 (ASV)

Sat at Jesus' feet. This was the ancient posture of disciples or learners. They sat at the feet of their teachers—that is, beneath them, in a humble place. Hence Paul is represented as having been brought up at the feet of Gamaliel (Acts 22:3). When it is said that Mary sat at Jesus' feet, it means that she was a disciple of his; that she listened attentively to his instructions, and was eager to learn his doctrine.