Allegiance is not an easy matter
Behaving according to the phrase “Labbayk Yā Mahdī (mgehr)”1 is much harder than the phrase “Labbayk Yā Ḥusayn (pbuh)”
When you say “Labbayk Yā Ḥusayn (pbuh)”; That means, ‘I am ready to help you’. Just as the martyrs of Karbalā, who helped Abū ʿAbd Allāh Ḥusayn (pbuh).