The Rasā'il Ikhwān al-safā' (The Epistles of the Brethren of Purity)
Stephen Lambden UC Merced.
From an old recenion of my 1980s doctoral thesis
1980s - under revision, 28-11-2018.
`The identity of the probably 4th/10th cent. Ikhwān al-Ṣafā’ (Brethren of Purity) is not known with any certainty. The fifty-two Rasā’il ascribed to them evidence a close relationship to Ismā’īlī doctrines, they "rewrote Neoplatonic and Pythagorean natural philosophy and metaphysics in Islamic terms" (Murata,1992:329). Their exposition of semi-esoteric "realities" sometimes goes beyond Islamic doctrinal norms. The authors of the Rasā’il were influenced by numerous streams of thought including Hermetic "wisdom" and the syncretistic "gnosis" of the Sabaeans of Ḥarrān. Yet these rasā’il "occupy a place in the first  rank of Arabic literature" having had an influence within both Sufism and Shī`īsm (Marquest EI2). The missionary Wolff, it is relevant to note here, reported that the Rasā’il were studied by the learned in early 19th century Shīrāz (MJ III: 53-4).
This was doubtless also the case in other Iranian locations. The vocabulary of the Bāb at times appears to reflect that of certain of the Rasā’il. 1 Some of the Rasā’il are indebted to the Bible, Greek philosophy and aspects of Jewish and Christian doctrine (Netton, 1982: 53ff; Marquet, EI2). The Ikhwān cited the HB and Rabbinic lore and had  some knowledge of the NT in several textual traditions. Moses and aspects of pentateuchal history and Islamo-biblical prophetology are occasionally present in the Rasā’il (R1:156-7; 186; 2:279ff; 4:16, 32). The reading of Abrahamic scripture and the Injīl (Gospel[s]) is recommended for these scriptures are said to result from angelic [divine] inspiration (bi’l-waḥy min al-malā’ika; cf. 4:42, 245; 1:363; 3:246; Netton 1983:54). The following citation allegedly mentioned in "certain of the books of the prophets of the children of Israel", is given in the form of a double post-qur’ānic revelation (ḥadīth qudsī),
"God, exalted be He said,
`O son of Adam, I created thee for all eternity (li’l-abd), for I am the Living One (al-ḥayy) who dieth not. So be obedient unto whatsoever I command thee and turn aside from whatsoever I prohibit thee.Then shall I make thee to be one who liveth eternally and dieth not (ḥayy an lā tamūt abad an).
1 e.g. R 2:277 a`lā al-`aliyyīn, "The most elevated of the exalted ones", although this matter is beyond the scope of this thesis. 
O son of Adam! I am Powerful (qādir an) such that I need only say to a thing, ‘Be!’ and it is (kūn fa-yakūn). [= Q.3:59, 6:72, etc] Then obey Me regarding whatever I have commanded thee and turn aside from whatever I have forbidden thee. Then shall I make thee one powerful (qādir an) such that thou need only say to a thing, `Be! and it shall be’ (kūn fa-yakūn)’ (R1:298).
Rewritten Genesis texts are clearly in evidence here (e.g Gen 3:22a). This is a scriptural citation which is obviously Islamicate possibly also reflecting a gnostic exaltation of the primordial man. The authors of the Rasā’il were aware of Jesus and of Christian doctrines and denominations (Monophysites, Jacobites [Ar. Ya`qūbī] and Nestorians R2:283-4). Jesus is quite often mentioned in the Rasā’il (R4:19; 2:232, 280; 3:287; 4:19, 42, etc). He is once designated by the Johannine, non-qur’ānic epithet "Son of the Father" (ibn al-āb, 2 Jn1:3). His "humanity" and divinity" are referred to by means of the Syriac Christological loan words nāsūt (Syr. `nāšūthā) and lāhūt ( Syr.`alāhūthā) respectively.1
1 These terms were early utilized by al-Ḥallāj (Massignon 1997:31) and subsequently used by many Sufi writers and in Bābī-Bahā’ī mystical cosmologies (R2:283-4; R2:367; R3:161; Netton 1982:55,122:fn.23).
The reality of the bodily crucifixion of Jesus is accepted in the Rasā’il. Jesus was taken before the "king of the children of Israel [Jews]" who ordered his crucifixion (bi-ṣalbihi). When  carried out Jesus’ nāsūt (humanity) was crucified (fa-suliba nāsūtihi). It is explicitly stated that his two hands were driven with nails (summarat) upon two wooden pieces of the cross (`alā al-khashabatayi al-ṣalīb). Jesus remained hanging crucified (maṣlūb an) from forenoon until the  afternoon (cf. Jn 19:31; R4: 31). These teachings obviously differ from the mainstream Muslim denial of Jesus’ bodily crucifixion though they are echoed in a tradition highly regarded and much cited by the Bāb (T. Baqara, 195; Q. Zavarih, 69:425, see below).
Important references to the Paraclete styled the baraqlī al-akbar (Greatest Paraclete) are found towards the beginning of the fifty-two Rasā'il (I:40) and twice in the related Risālat al-Jāmi`a ("Comprehensive Epistle", II:354, 365). This Islamic Paraclete is twice associated with the expected Mahdī in the Rasā’il (al-mahdī al-muntazar; R. 1:40; J. 2:365, Netton, 1982:68).