Imam Ali (AS) narrated from the Prophet of Islam (PBUH) who said:

For every good deed there is another higher good deed, except martyrdom in the way of Allah (SWT) which there is no better deed than that. And there is another worse act for every unkind act, except murder of the father or the mother which there is no worse act than that [1].

[1] From the book of Nasim-e-Sahar.

Source: en.shafaqna.com