PURPORT

Although, by chance, the doormen committed a mistake by checking the brahmanas from entering the gate of Vaikuntha, they were at once aware of the gravity of the curse. There are many kinds of offenses, but the greatest offense is to offend a devotee of the Lord. Because the doormen were also devotees of the Lord, they were able to understand their mistake and were terrified when the four Kumaras were ready to curse them.