This third part of Poorv Bhaag of Naarad Puraan is about Sa-Kaam worship - worshipping Shiv, Vishnu, Raam, Hanumaan, and Krishn.

Worship

Sanat Kumaar Jee said - "Two Shankh, two Chakrashilaa (Gomatee Chakra), two Shiv Ling, two Ganesh idols, two Soorya idols, three Durgaa idols should not be worshipped in one house. This harms the family. After doing the worship, all worshippers should take Charanaamrit and Prasaad from the Naivedya offered to their Isht Dev. Anything offered to Bhagavaan Shiv is not worthy to take, but as soon as it touches Shaaligraam stone, it becomes all holy and acceptable.

Five kinds of worship have been told - Aaturee, Sautikee, Traasee, Saadhanaabhaavinee, and Daurbodhee. 

(1) Aaturee Poojaa - A patient should neither take bath, nor do Jap, nor worship. He should do only Darshan of his Isht Dev (idol, or Soorya's Darshan), remember his Mantra and offer flowers. When he becomes all right, then he should take bath, salute his Guru and pray that "By the grace of your Prasaad, I should not be blamed to abandon Poojaa." After taking his blessings he should resume his Poojaa. Feed Braahman and give Dakshinaa. 
(2) Sautikee Poojaa - Sootak is of two types - Jaat Sootak Sootak) and Mrit Sootak (Paatak). In both kinds of Sootak, one should do only mental worship. After Sootak is over, one can resume normal worship after taking blessings of Guru and Braahman.
(3) Traasee Poojaa - Who has been afflicted by his enemies, he should do worship with whatever is available to him or even mentally. 
(4) Saadhanaa-bhaavinee Poojaa - When one cannot get Poojaa materials and does Poojaa only with available leaves, flower or fruits; or mentally, it is called S aadhanaa-bhaavinee Poojaa. 
(5) Daurbodhee Poojaa - A woman, an old man, a child and a fool worship in whatever way because of their A-Gyaan (ignorance), that is called Daurbodhee Poojaa.

Thus a Saadhak can do any kind of Poojaa. After doing Poojaa, one should feed Braahman and take Prasaad from the offered Naivedya to Isht Dev. Then after taking rest he may read or listen to Puraan or Itihaas. Who does not do Poojaa methodically in spite of having and knowing everything, he does not get the whole fruit of that Poojaa.

Mantra

Naaraayan Mantra-8-letter Mantra
Sanat Kumaar Jee said - "Now I tell you about the Mantra for Vishnu which are scarcely available and by which one can fulfill his desires easily. "Aum Namo Naaraayanaaya" - this is 8-letter Mantra. It belongs to Saadhya Naaraayan Rishi. Vishnu is its Devtaa, Aum is its Beej, Namah is its Shakti (power). It is used to fulfill all kinds of desires. 

(1) Who does Jaap of this Mantra 25 times daily before taking water, he becomes free from all kinds of sins, learned and healthy.
(2) If at the time of solar and lunar eclipses, one touches the Ghee and then do the Jaap of this Mantra 8,000 times; and after the eclipse is clear, the Saadhak drinks that ghee, he attains the power of speaking, writing poems and intelligence.

This Naaraayan Mantra is the best among all of the Mantra. Its Vishnu Gaayatree Mantra is "Aum Naaraayanaaya Vidmahe Vaasudevaaya Dheemahi Tanno Vishnu Prachodayaat" and it destroys all kinds of sins.

\ Vaasudev Mantra-12-Letter Mantra
Dwaadash Akshar (12-letter) Mantra - For Krishn/Naaraayan - "Aum Namo Vaasudevaaya". Women and Shoodra should do its Jaap without "Aum". Others can do its Jaap with "Aum". This Mantra's Prajaapati is Rishi, Chhand is Gaayatree, Devtaa is Vaasudev, seed is "Aum", and power is "Namah". Its Jaap should be done 1,200,000 times, its Havan should be done by its one tenth number (120,000) times with sesame seeds and Ghee.

[Here several Nyaas methods are given.]

This Mantra section is very elaborated. It is not given here in full.