Is wearing trousers under the abaya a condition for prayer if the abaya completely covers the body?

For the prayer to be valid, it is a condition that a woman's body be covered, with the exception of the face and hands. If the abaya covers the body, it is sufficient. However, if it does not cover, for example, the lower parts of the legs, then it is obligatory to wear something that covers them, such as trousers. It is disliked for a woman to pray in trousers alone; it is preferable for her to wear an abaya over them. Imam Al-Shafi'i said: "The state of a woman in this regard is more stringent than that of a man. If she prays in a shift and head covering that describe her figure, I would prefer that she does not pray except in a jilbab over that, keeping it loose from her so that the shift does not describe her."