basis refers to the feet in the healing scene where a man's feet and ankles are strengthened.

The attested use names the feet in the scene where a man is raised up and his feet and ankles are strengthened.

1. Feet strengthened in healing · dominant

   In Acts 3:7, the nominative plural feminine form occurs in the clause about a man being raised up; the APB renders the verse with his “feet and ankles” being strengthened.

   Acts 3:7

In the Anselm Project Bible: In Acts 3:7, the APB presents the clause as the strengthening of “feet and ankles.” Its exact division of that wording between the original terms cannot be determined.