Vijnanakaya or Vijnanakaya-sastra is one of the seven Sarvastivada Abhidharma Buddhist scriptures. "Vijnanakaya" means "group of consciousness". It was composed by Devasarman (according to both Sanskrit and Chinese sources), with the Chinese translated by Xuanzang: T26, No. 1539, 阿毘達磨識身足論, 提婆設摩阿羅漢造, 三藏法師玄奘奉 詔譯, in 16 fascicles.
Vijnanakaya is the first Abhidharma text that is not attritubted to a direct disciple of the Buddha, but written some 100 years after the Buddha's parinirvana, according to Xuanzang's disciple Puguang. Yin Shun however, concludes it was composed around the 1st century CE, and was influenced by the Jnanaprasthana, though differs in several aspects. In this regard, he likens it to the Prakaranapada, which is also a different position on the Sarvastivada as a whole.
This is an esteemed Sarvastivada text wherein the Sarvastivada is upheld against Vibhajyavada objections, in the first of its six sections. It is here that the theory of sarvastivada, the existence of all dharmas through past, present and future, is first presented. Interestingly, the issue is only brought up when Moggaliputta-tissa makes the standard claim of the Vibhajyavada, "past and future (dharmas) do not exist, (only) present and unconditioned (dharmas) do exist". The Vijnana-kaya has four main theses to refute this:
The impossibility of two simultaneous cittas
The impossibility of karma and vipaka being simultaneous
That vijnana only arises with an object
Attainments are not necessarily present.
In addition to refuting the Vibhajyavada view, the second section is a refutation of the Vatsiputriya Pudgalavada claim of: "the paramartha of the arya truths can be attained, can be realized by the 'pudgala', present and complete, therefore it is certainly [the case] that the 'pudgala' exists". The Sarvastivada take the title 'Sunyavada' in order to refute this claim, though this is obviously meaning "empty of pudgala", rather than the later Sunyavada of the Mahayana, i.e. the Madhyamaka. The first refutation centers around the two extremes of "absolute identity" and "absolute difference". The second hinges on the continuity of the existence of the skandhas in the past, present and future – sarvastivada – proper.
The third and fourth sections concern the causal condition, and the conditioning object of vijnana respectively. The fifth includes the two other conditions, the immediate condition and predominant condition. These conditions are discussed in terms of their realm, nature, temporal location, etc. in a format that came to be standard for the Sarvastivada Abhidharma. Such a system also appears in Abhidharma type analysis of dharmas in the Mahaprajnaparamita Sutra and its Upadesa. The remaining five sections are doctrinal elaborations of the Sarvāstivāda school, including issues regarding perception, dependent origination and conditionality.