Fātimah is a piece of me, so whoever makes her angry makes me angry
Authentic hadithعن المسور بن مخرمة رضي الله عنهما مرفوعًا: «فاطمة بَضْعة مني، فمَن أغضبها أغضبني».
Al-Miswar ibn Makhramah (may Allah be pleased with him) reported that the Prophet (may Allah's peace and blessings be upon him) said: "Fātimah is a piece of me, so whoever makes her angry makes me angry."
Explanation
The Prophet (may Allah's peace and blessings be upon him) informs that his daughter Fātimah is part of him. So anyone who makes her angry, it is as if he angered the Prophet (may Allah's peace and blessings be upon him).
Source · Narrated by Bukhari & Muslim
From the Hadith Encyclopedia (hadeethenc.com).