Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) says: The major sins are: associating partners with Allah, feeling secure from the plan of Allah Almighty, despairing of the mercy of Allah Almighty, and losing hope in His relief.
In one narration the words are: "The greatest of the major sins." Its chain is sahih (authentic).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الإيمان / 392
Hadith Gradingمحدثین:إسناده صحیح
Hadith Takhrij«اخرجه الامام الطبراني فى معجمه الكبير 8783 ، 8784 ، 8785»