Out of many millions of wandering living entities, one who is very fortunate gets an opportunity to associate with a bonafide spiritual master by the grace of Krishna. By the mercy of both Krishna and the spiritual masters, such a person receives the seed of the creeper of devotional service.
The spiritual master is the mercy representative of the Lord.
Srimad Bhagavatam 1.7.22,
Srila Prabhupada
If we take shelter of the lotus feet of the spiritual master, we can become free from illusion, fear and distress. If we wholeheartedly beg for his mercy without any deceit then the spiritual master bestows all auspiciousness upon us.
When you come before spiritual master, be prepared to get chastised. Spiritual Master’s business is to do that. Shisya means who is ready is accept ‘sashan’ or ready dor getting chastisement.