What is the ruling on someone who intended to perform Hajj on behalf of his mother instead of his father, after he was asked to perform Hajj on behalf of his father? And is it permissible to slaughter the sacrificial animal before the Day of Sacrifice? And is it permissible for one person to stone on behalf of more than 36 pilgrims?

As for errors in the talbiyah (definition), they do not matter as long as the intention is directed towards the person on whose behalf the Hajj is performed, for what counts is what is in the heart, not what is on the tongue. As for delaying the sacrifice until the Day of Sacrifice, that is preferable, but it is permissible to sacrifice before it. Finally, a person may throw on behalf of one or more without limitation, as long as he is able to do so.