By a farbrengen once the subject of the pesukim for the Rebbe (at the end of shmoneh esreh, when we say pesukim for our name and the Rebbe’s name) came up.
The Rebbe wrote that his pesukim are מאור עינים ישמח לב and מה טובו. I think that was mentioned then, but when the subject came up, Reb Mendel said unequivocally and forcefully "The possuk of the Rebbe is מגדיל ישועות מלכו ועושה חסד למשיחו לדוד ולזרעו עד עולם" in a way that left no possibility of argument. He said it with such תוקף and conviction that he affected me, so that even though I couldn't stop saying the pesukim that the Rebbe mentions, I also couldn't not say magdil, so since then (which is many years) I've been saying magdil, and then me'or einayim and mah tovu, and then my pesukim (which is the secret of why my shemoneh esreh takes a little longer....).
