Not only was Rabbi Israel [Salanter] opposed to the performance of the finer points of mitzvot at the expense of human beings, he held that one had no right even to perform the essentials of a mitzvah or even extricate himself from grievous sin if he thereby inflicted suffering on someone else.
A question was submitted to him: Someone had sinned in secret against a friend of his by speaking evil of him. Was it permissible for this person now to go to his friend and seek forgiveness? In so doing, however, he would have to disclose what he had said to the friend he had maligned.
Rabbi Israel [Salanter] ruled, that although the questioner would absolve himself from grievous guilt by seeking his friends forgiveness, he had no right to pursue his own good by hurting his friend - enhancing his righteousness at the expense of causing distress to someone else. This is the extent to which R. Israel took the feelings of others into account, how he engaged in complicated calculations so as to avoid giving any hurt or distress to others. -- The Mussar Movement, Volume 1, Part 2 pages 229 - 230
The Baal Shem Tov once traveled with a group of his disciples to a distant village where there lived a certain parush (ascetic) who was constantly engaged in Torah study, prayer, and other divine service, to the exclusion of everything else. He was totally indifferent to worldly affairs. Whenever he uttered any words of Torah, he added, "So I received it from Elijah the Prophet." He was also an exceptional teacher who possessed a remarkable ability to clarify a complex Torah topic for anyone to whom he spoke, even the simplest person. Who could be more exalted?