The Pope told priests that if they "anoint" others by bringing the grace of God to their everyday realities, they will be strengthened in their priesthood.

"A good priest can be recognized by the way his people are anointed," said Pope Francis during the Holy Thursday Chrism Mass at which oils that will be used in the sacraments are blessed.

"When our people are anointed with the oil of gladness, it is obvious, for example, they leave Mass looking as if they have heard good news," he said at Saint Peter's Basilica on March 28.

Pope Francis noted that priests must to "go out in order to experience anointing, its power and its redemptive efficacy."

He illustrated what he meant by recalling the image of Aaron being anointed with oil as High Priest of Israel.

"A fine image of this 'being for' others can be found in the Psalm: 'It is like the precious oil upon the head, running down upon the beard, on the beard of Aaron, running down upon the collar of his robe' (Ps. 133:2)," the Pope recalled.

"The image of spreading oil, flowing down from the beard of Aaron upon the collar of his sacred robe, is an image of the priestly anointing which, through Christ, the Anointed One, reaches the ends of the earth, represented by the robe," he said.

Pope Francis warned that priests who do not do this "grow dissatisfied, become sad and lose heart."

"We need to 'go out' … to the outskirts where there is suffering, bloodshed, blindness that longs for sight, and prisoners in thrall to many evil masters," he told hundreds of priests.

This afternoon, Pope Francis will put his challenge into action by celebrating the Mass of the Last Supper at Casal del Marmo, a youth prison on the northwest side of Rome.

During the Mass, he will wash the feet of 12 inmates who come from different faiths and ethnicities.

"A priest who seldom goes out of himself, who anoints little (…) misses out on the best of our people, on what can stir the depths of his priestly heart," said Pope Francis.

"People thank us because they feel that we have prayed over the realities of their everyday lives, their troubles, their joys, their burdens and their hopes," he observed.

The Holy Father added that when people feel "that the fragrance of the Anointed One, of Christ," has come to them through priests, they feel encouraged to entrust to them everything they want from God.

Pope Francis also called for more unity between priests and lay people.

"Dear lay faithful, be close to your priests with affection and with your prayers, that they may always be shepherds according to God's heart," he urged.

This morning's Mass was significant because it is the only day of the year that the sacred oils for Baptism, Confirmation and Anointing of the Sick are blessed.

After his homily, Pope Francis received and blessed three huge silver urns of the different oils.

Following the ceremony, they were taken back to the sacristy and distributed among the priests of the diocese who took them away in silver vessels.

The remaining oil is then traditionally securely guarded under lock and key.