Shaikh Sharafuddin Yahya al Maneri (Allah have mercy on him) said,

‘A disciple is a person who submits himself to his guide in word, deed, heart and body.’

He went on to explain:
” ‘In words’ means that his speech is in conformity with what his guide says regarding the essential principles and derived teaching of religion.

‘In deeds’ means that he does nothing, whether in a religious or worldly matter, contrary to what has been sanctioned by his guide, even if it be an act of devotion!

‘In heart’ means keeping his heart unstained by any blameworthy quality, just as his guide does.

‘In body’ means keeping his senses and bodily members pure and without any stain of sin, just as his guide has done.

When he has conformed himself in all these ways, then he can be called a disciple.”

A Mine of Meaning (Ma’din ul–Ma’ani), page 165