Is the prayer valid when the Abrahamic prayer (Salat al-Ibrahimiyyah) is recited in the last tashahhud without reciting the tashahhud?

The Tashahhud is a pillar of prayer; prayer is not valid without it. And whoever is ignorant of an obligatory act in worship and performs it incorrectly, then he is excused, and he is not required to repeat the past acts of worship. He must, however, correct his worship in the future. It is obligatory upon every Muslim to learn the rulings of the acts of worship incumbent upon him.