St. Gertrude saw Jesus lift souls from purgatory to Heaven according to the number of prayers offered for them.
St. Gertrude the Great was a holy mystic of the 14th century, who received many heavenly visions as a Benedictine nun. Among her numerous private revelations were short glimpses into purgatory.
One such vision is described in the book The Life and Revelations of Saint Gertrude and highlights the power of prayer for the souls in purgatory.
On Wednesday, at the elevation of the Host, she besought our Lord for the souls of the faithful in purgatory, that He would free them from their pains by virtue of His admirable Ascension; and she beheld our Lord descending into purgatory with a golden rod in His Hand, which had as many hooks as there had been prayers for their souls; by these he appeared to draw them into a place of repose. She understood by this that whenever any one prays generally from a motive of charity for the souls in purgatory, the greater part of those who during their lives have exercised themselves in works of charity, are released.
The Catholic Church teaches that the souls in purgatory are still in some mysterious way connected to the Church on earth and our prayers have an effect on their time spent in this final stage of purification.
St. Gertrude is one of the most well-known saints who advocated for these holy souls in purgatory, and the Church often refers to her and her visions to help explain the concept of purgatory.