1) Medea, in order to rejuvenate Jason's father she cut his throat to let the old blood run out, dismembered him, putting the pieces in a caldron with the liquid herbs she had prepared.
Jason’s father emerged from the caldron rejuvenated, forty years younger.

2) Medea’s spell captured the daughters of Pelias. The daughters also wished to rejuvenate their father and Medea said she would perform the task again. The daughters prepared their father by dismembering him; however, this time Medea did not put the herbs in the caldron and their father never emerged.

3) Later on, Medea was mad at Jason so as revenge, she murdered her own children to avenge Jason's infidelity.