No. Slotted abilities with passives don't proc it. Read the text exactly and it is a little more clear after this comment, hopefully!
PC NA @gariondavey, BG, IC & Cyrodiil Focused Since October 2017 Stamplar (main), Magplar, Magsorc, Stamsorc, StamDK, MagDK, Stamblade, Magblade, Magden, Stamden
But for example, casting my armor buff on a templar gives major buff. And if I stand in it I get minor mending because of templar passive. So the minor mending procs it, even though I didn't cast an ability that gives minor mending directly. But the buff of minor mending had to be applied to me.
PC NA @gariondavey, BG, IC & Cyrodiil Focused Since October 2017 Stamplar (main), Magplar, Magsorc, Stamsorc, StamDK, MagDK, Stamblade, Magblade, Magden, Stamden