My question is: for Eid-ul-Adha, can we weigh the animal of Qurbani and then purchase it, or not?
It is permissible to weigh an alive animal and purchase it, but Qurbani should be done for the pleasure of Allah.
Ruling on performing Qurbani (i.e. the animal sacrifice) with an animal that appears older than its actual age.
English 2 Rules for the SecrificeRuling on Offering Qurbani in the Event of Lost, Injury or Death of the Sacrificial Animal
English 0 Rules for the Secrifice