Since devotion to the spiritual master is so fundamental to the development of devotion to Krishna, Srila Prabhupada instituted several practices in ISKCON temples that help to instill and inculcate this. For instance, the daily routine worship in all ISKCON temples begins at 4.15 am. All resident devotees are expected to unfailingly rise early and attend this first worship called mangala arati. This mangal arati begins with the devotees singing the guruvashtaka, a song of eight stanzas, glorifying the spiritual master. The devotees repeatetle sing this refrain:

vande guroh sri charanaravindam:
I offer my obeisance to the spiritual master.

This song describes the important theological aspects of the spiritual master that every disciple should know and internalize. Hence the worship of Krishna begins every day in all ISKCON temples with the worship of the spiritual master. This is the most fundamental principle of spiritual life that every devotee learns.

Daily worship of the Spiritual Master
Srila Prabhupada introduced yet another daily worship called Guru Puja that takes place at about 7.30 am in all ISKCON temples. The devotees offer a special arati to the Deity of Srila Prabhupada seated on a revered seat (Vyasaasana) and sing a Bengali song composed by a 17th century devotee-saint coming in the tradition of Sri Chaitanya Mahaprabhu. This intensely devotional song describes the theological principles about the position of the spiritual master and emphasizes the role of the guru in a devotee's life.

“The spiritual master has given me the gift of
transcendental vision and I shall remain his
servant birth after birth. By his mercy, divine
knowledge is revealed within the heart,
bestowing prema-bhakti and destroying
ignorance. The Vedic scriptures sing of his
character.”

There are hundreds of instances when Srila Prabhupada instructed this central role an Acharya plays in the life of a disciple.

The qualifications of such an Acharya

In order to play that role of an Acharya, one mus t have extraordinary spiritual qualifications and purity. Only a pure devotee of Krishna who is free from lust, false ego and material motivations can receive such worship and honor on par with God and remain unaffected by it. In such a spiritually elevated state one can receive such adoration and pass on all of it to Krishna and act as a transparent via media to God. Such great souls are indeed very rare. Srila Prabhupada had taught this too.

When one has attained the topmost
position of mahä-bhägavata, he is to be
accepted as a guru and worshiped exactly
like Hari, the Personality of Godhead. Only
such a person is eligible to occupy the post
of a guru. (Chaitanya Charitamrita Madhya
24.330).

Srila Prabhupada had quoted a verse from the Padma Purana that says the spiritual master or
guru should be a maha-bhagavata shreshta:

The guru must be situated on the topmost
platform of devotional service. There are
three classes of devotees, and the guru
must be accepted from the topmost class.
(Chaitanya Charitamrita Madhya 24.330).

In a letter to a disciple, Srila Prabhupada had explained the exalted position of the spiritual
master:

Unless one is a resident of Krishna Loka,
one cannot be a Spiritual Master. That is
the first proposition. A layman cannot be a
Spiritual Master, and if he becomes so then
he will simply create disturbance. (Letter
to Mukunda, June 10th, 1969).