To preach the Gospel for praise is bad business especially when people stop praising you. Find your praise in the testimony of a good conscience.
 Martin Luther, Commentary on the Epistle to the Galatians (1535). copy citation

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Author Martin Luther
Source Commentary on the Epistle to the Galatians
Topic praise conscience
Date 1535
Language English
Reference
Note Translated by Theodore Graebner
Weblink http://www.gutenberg.org/files/1549/1549-h/1549-h.htm

Context

“(II Cor. 6:8.)
The Gospel entails persecution. The Gospel is that kind of a doctrine. Furthermore, the disciples of the Gospel are not all dependable. Many embrace the Gospel today and tomorrow discard it. To preach the Gospel for praise is bad business especially when people stop praising you. Find your praise in the testimony of a good conscience. This passage may also be applied to other work besides the ministry. When an official, a servant, a teacher minds his business and performs his duty faithfully without concerning himself about matters that are not in his line he may rejoice in himself.” source