One of the Major Sins is to Abuse Your Parents

Hazrat Abdullah Bin Umar (R.A) Narrates That The Holy Prophet (P.B.U.H) Said;

One of the major sins is to abuse your parents. A Companion Asked How Can A Person Abuse His Parents. The Holy Prophet (P.B.U.H) replied. "If He Abuses Someones Father, That Person Abuse Back at His Father. And If He Abuses at Someones Mother ,That Person will Abuse Back His Mother".

(Bukhari & Muslim)