Hazrat Shaikh Moulana Muhammad Zakariyya (rahmatullahi ‘alaih) once mentioned the following in a letter he wrote to a certain person:
My Hazrat (i.e. Hazrat Moulana Khaleel Ahmad Sahaaranpuri [rahimahullah]) once wrote a letter to me in which he mentioned, “My example is like that of a water pump through which water is drawn out from the well. The more effort a person makes when pumping water from the well, the more water he will receive from the source (i.e. the well). In other words, I am just the medium through which you will benefit and receive from Allah Ta‘ala, just as the water pump is the medium to receive the water.”
Addressing the person in the letter, Hazrat Shaikh Moulana Muhammad Zakariyya (rahmatullahi ‘alaih) then said:
The reality of the matter is exactly like this (how Hazrat Moulana Khaleel Ahmad Sahaaranpuri [rahimahullah] said). You wrote to me mentioning that you understand that your involvement in the effort of Da’wat and Tableegh is a means for you to progress, and your leaving the work is a means for you to retrogress. Undoubtedly, the effort of Da’wat and Tableegh is a means for one to make abundant progress, and the more effort you make in this path, insha-Allah the more you will progress.
However, together with engaging in the effort, in order for you to progress, it is necessary for you to be mindful of two important aspects. The first aspect is that you must always remain extremely fearful and concerned that no trace of pride or self-admiration should enter your heart at any time. The people who are engaged in the effort of Deen – especially those engaged in the effort of Da’wat and Tableegh – Shaitaan makes a concerted effort upon them to mislead them through this way (i.e. he tries his level best to mislead them by creating pride in their hearts).
The second aspect is that it is extremely important and necessary for you to remain connected to the markaz, and be connected to the elders of the effort of Da’wat and Tableegh, as this is the powerhouse (through which you will gain direction and guidance).
(Qutbul Aqtaab Hazrat Shaikhul Hadith Moulana Muhammad Zakariyya [rahmatullahi ‘alaih] pg. 414-415)