Srimad Bhagavatam Canto 04, Chapter 01, Text 15

SB 4.1.15

atreh patny anasuya trin
jajne suyasasah sutan
dattam durvasasam somam
atmesa-brahma-sambhavan
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
Anasuya, the wife of Atri Muni, gave birth to three very famous sons  Soma, Dattatreya and Durvasa  who were partial representations of Lord Visnu, Lord Siva and Lord Brahma. Soma was a partial representation of Lord Brahma, Dattatreya was a partial representation of Lord Visnu, and Durvasa was a partial representation of Lord Siva.
 
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
In this verse we find the words atma-isa-brahma-sambhavan. Atma means the Supersoul, or Visnu, isa means Lord Siva, and brahma means the four-headed Lord Brahma. The three sons born of Anasuya  Dattatreya, Durvasa and Soma  were born as partial representations of these three demigods. Atma is not in the category of the demigods or living entities because He is Visnu; therefore He is described as vibhinnamsa-bhutanam. The Supersoul, Visnu, is the seed-giving father of all living entities, including Brahma and Lord Siva. Another meaning of the word atma may be accepted in this way: the principle who is the Supersoul in every atma  or, one may say, the soul of everyone  became manifested as Dattatreya, because the word amsa, “part and parcel,” is used here.
 
In Bhagavad-gita the individual souls are also described as parts of the Supreme Personality of Godhead, or Supersoul, so why not accept that Dattatreya was one of those parts? Lord Siva and Lord Brahma are also described here as parts, so why not accept all of them as ordinary individual souls? The answer is that the manifestations of Visnu and those of the ordinary living entities are certainly all parts and parcels of the Supreme Lord, and no one is equal to Him, but among the parts and parcels there are different categories. In the Varaha Purana it is nicely explained that some of the parts are svamsa and some are vibhinnamsa. Vibhinnamsa parts are called jivas, and svamsa parts are in the Visnu category. In the jiva category, the vibhinnamsa parts and parcels, there are also gradations. That is explained in the Visnu Purana, where it is clearly stated that the individual parts and parcels of the Supreme Lord are subject to being covered by the external energy, called illusion, or maya. Such individual parts and parcels, who can travel to any part of the Lord’s creation, are called sarva-gata and are suffering the pangs of material existence. They are proportionately freed from the coverings of ignorance under material existence according to different levels of work and under different influences of the modes of material nature. For example, the sufferings of jivas situated in the mode of goodness are less than those of jivas situated in the mode of ignorance. Pure Krsna consciousness, however, is the birthright of all living entities because every living entity is part and parcel of the Supreme Lord. The consciousness of the Lord is also in the part and parcel, and according to the proportion to which that consciousness is cleared of material dirt, the living entities are differently situated. In the Vedanta-sutra, the living entities of different gradations are compared to candles or lamps with different candlepower. For example, some electric bulbs have the power of one thousand candles, some have the power of five hundred candles, some the power of one hundred candles, some fifty candles, etc., but all electric bulbs have light. Light is present in every bulb, but the gradations of light are different. Similarly, there are gradations of Brahman. The Visnu svamsa expansions of the Supreme Lord in different Visnu forms are like lamps, Lord Siva is also like a lamp, and the supreme candlepower, or the one-hundred-percent light, is Krsna. The visnu-tattva has ninety-four percent, the siva-tattva has eighty-four percent, Lord Brahma has seventy-eight percent, and the living entities are also like Brahma, but in the conditioned state their power is still more dim. There are gradations of Brahman, and no one can deny this fact. Therefore the words atmesa-brahma-sambhavan indicate that Dattatreya was directly part and parcel of Visnu, whereas Durvasa and Soma were parts and parcels of Lord Siva and Lord Brahma.
Srimad Bhagavatam Canto 04, Chapter 01, Text 14
Srimad Bhagavatam Canto 04, Chapter 01, Text 16