50 On the other hand, by sincere disinterestedness the priest can hope to win the hearts of all. For detachment from earthly goods, if inspired by lively faith, is always accompanied by tender compassion towards the unfortunate of every kind. Thus the priest becomes a veritable father of the poor. Mindful of the touching words of his Savior, "As long as you did it to one of these My least brethren, you did it to Me," he sees in them, and, with particular affection, venerates and loves Jesus Christ Himself.
Source: Ad Catholici Sacerdotii (Vatican.va)