This hadith shows the special status of Imam Ali, Lady Fatimah, Hasan and Husain in Islam. The Holy Prophet (PBUH) announced "I am in war with that person who is in war with you and I am in peace with that person who is in peace with you"
English Translation:
Sayyidina Zayd ibn Arqam (RA) reported that Allah’s Messenger (SAW) said to Ali, Fatimah, Hasan and Husain,
"I am in war with that person who is in war with you and I am in peace with that person who is in peace with you"