John Chrysostom

"Or ministry, let us wait on our ministering." Here he names a comprehensive thing. For the Apostleship even is called a ministry, and every spiritual work is a ministry. This is indeed a name of a peculiar office (viz. the diaconate); however, it is used in a general sense. "Or he that teacheth, on teaching." See with what indifference he places them, the little first and the great afterwards, again giving us the same lesson, not to be puffed up or elated.

Homily on Romans 21 ↗

Theophylact of Ohrid

There is a ministry and a special gift in the church order, such as the ministry of the seven deacons. But here by the name "ministry" understand generally every spiritual work. Whatever ministry, he says, you have received, "abide" in the fulfillment of it (this word must be supplied here), do not seek anything greater, and do not exalt yourself above another, but be content with what you have received. If one takes ministry in a general sense, then what follows is an enumeration of its types. …

Commentary on Romans ↗

Thomas Aquinas

In regard to administering the sacraments he adds: or ministry, in ministering, i.e., if one has received the grace or office of the ministry, such as the bishop or priest who are called God's ministers—you shall be called the priests of the Lord, the ministers of our God (Isa 56:6)—let him perform his office diligently in ministering: fulfill your ministry (2 Tim 4:5). Second, he touches on matters pertinent to human affairs in which one person can help another: first, with respect to knowledge both speculative and practical. …

Commentary on Romans ↗