According to Srila Visvanatha Cakravarti Thakura, there are two kinds of impediments to devotional service. The first is an offense at the lotus feet of a Vaisnava. This is called vaisnava-aparadha. Sri Caitanya Mahaprabhu warned His devotees not to commit vaisnava-aparadha, which He described as the mad elephant offense. When a mad elephant enters a beautiful garden, it destroys everything, leaving a barren field. Similarly, the power of vaisnava-aparadha is so great that even an advanced devotee becomes almost devoid of his spiritual assets if he commits it. Since Krsna consciousness is eternal, it cannot be destroyed altogether, but advancement may be checked for the time being.

Srila Prabhupada; Srimad Bhagavatam 5.1.5 purport