Dialogue between Krsna and Satyabhama as described in Padma Purana:
The sins accumulated by various Kalpas vanish in an instant when a lamp in offered during Karthik.

There is no value of even the Ashwamedha sacrifices for someone who in this month offers ghee lamps to the Lord. By this offering, all prescribed activities, even if devoid of Mantra, rituals and cleanliness are brought to perfection. Anyone who offers lamp to Lord Kesava during Karthik is actually performing all sorts of abulations and sacrificial ceremonies.

It was in this month that the child Druva quickly obtained the vision of The Supreme Lord Hari by worshipping Him although He can rarely be seen even by great yogis.

A person who in this month elevates a lamp high in the sky delivers his family and reaches the abode of The Lord.

These dipas will bring wealth, abundance, prosperity, all sorts of opulence, progeny, a benign glance and wisdom.

Anyone who arranges a Karthik lamp in their house will gain the results of an Agni stoma sacrifice.

During Karthik a person who bathes or gives alms, no matter where, earns the merit of an Agni-hotra sacrifice and results are even more if this pious deed includes worship as well.

A person who settles a lamp on the dome or within the temple delivers hundreds of generations in his lineage even if he is hired.

In the family of those who admire with great devotion the illuminated temple of The Lord no one will ever experience hell.

Observing a human offering a lamp to The Lord, even the Devatas think, when will I get his association.

A person who arranges a Dipa inside and outside the Lord’s temple is assured that in his family line hundreds of thousands will not go to hell.

A person who arranges a Dipa mala inside and outside the Lord’s temple will surely leave for the supreme abode on the path illuminated by those very dipas.

Naradiya Purana, dialogue between Rukmangada and Mohini.
Between the offering of all existing wealth and the offering of a lamp during Karthik there is no comparison – in fact, the latter is certainly more precious.

Skanda Purana, dialogue between Brahma and Narada:
All the results acquired by donating grains during Pitra Paksa or by distributing water in the months of Jyetshta or Asadha are easily gained in the course of Karthik merely by reviving a lamp offered by someone else. In this month, the fruits of Rajasuya and Ashwamedha sacrifices are attainable just by reviving another’s lamp and by serving the Vaisnavas.

Once even a mouse attained a rare human form and reached the Supreme destination after reviving a lamp on Ekadasi.

Even one who never performs a religious ritual or even the worst sinner will be purified by this offering. All the born or to-be-born members of the family, including all the innumerable forefathers will enjoy in heaven for a long time and will obtain liberation by the grace of Lord Hari, who has a Cakra in his hand.