The execution of devotional service during Ūrja-vrata in the month of Kārttika is especially recommended to be performed at Mathurā. This system is still followed by many devotees. They go to Mathurā or Vṛndāvana and stay there during the month of Kārttika specifically to perform devotional services during this period.
In the Padma Purāṇa it is said: "The Lord may offer liberation or material happiness to a devotee, but after some devotional service has been executed, particularly in Mathurā during the month of Kārttika, the devotees want only to attain pure devotional service unto the Lord." The purport is that the Lord does not award devotional service to ordinary persons who are not serious about it. But even such unserious persons who execute devotional service according to the regulative principles during the month of Kārttika, and within the jurisdiction of Mathurā in India, are very easily awarded the Lord's personal service.
In the Bhaviṣya Purāṇa there is a statement about observing different ceremonies celebrating the Lord's appearance (birthday) and other transcendental activities. It is said, "My Lord Janārdana (Kṛṣṇa), please let us know the date when Your mother Devakī devī gave birth to You. If You kindly inform us about this, then we shall observe a great celebration on this date. O killer of Keśī, we are souls one hundred percent surrendered unto Your lotus feet, and we wish only to please You with our ceremonies."
This statement of the Bhaviṣya Purāṇa gives evidence that by observing different functions in relationship with the Lord one is sure to become pleasing to the Lord. It is said in the Ādi Purāṇa: "A person who is constantly engaged in chanting the holy name and who feels transcendental pleasure, being engaged in devotional service, is certainly awarded the facilities of devotional service, and is never given just mukti (liberation)."
Mukti means liberation from material contamination; when liberated, one does not have to take birth again in the material world. The impersonalists desire to merge into the spiritual existence, to end their individual existence, but according to Śrīmad-Bhāgavatam, mukti is only the beginning of one's becoming situated in his normal condition. The normal condition of every living entity is to be engaged in the devotional service of the Lord. From the statement of the Ādi Purāṇa it appears that a devotee is satisfied simply with being engaged in devotional service. He does not aspire for any liberation from material conditional life. In other words, anyone who is engaged in devotional service is not in the material condition of life, although he may appear so.