Of what did the Franciscans take a vow?

Franciscans take a vow of evangelical poverty, which is the "strong" version of the vow of poverty. They can own no personal property ... Some religious orders take a different sort of vow of poverty, which allows them to own property but not to use it for their own benefit. Franciscan.

Explanation:

Franciscan, any member of a Roman Catholic religious order founded in the early 13th century by St. Francis of Assisi. The Franciscan order is one of the four great mendicant orders of the church, and its members strive to cultivate the ideals of poverty and charity.