In my last article about the life and work of Abu Ma’shar I said that Al-Biruni in his book “On Transits” testifies about the connection between Valens and Abu Ma’shar but I didn’t had the quote in hand to point out the needed reference in the particular book by Al-Biruni.
Here’s the quote:
And when Abu Ma’shār transferred to the Great Introduction the elements (of astrology) from al-Bizīdhaj (The Anthology), he mentioned that the Persians called the first type which is equipollent (lit. corresponding in strength) potent, and the type which is corresponding in ascension he called corresponding in course, and he left the third type as it is. And when Abū Muḫammad al-Saifī has mentioned it and called the first type equipollent and he called it also corresponding in course. And he judged Abu Ma’shār (adversely) for calling the second type the ones corresponding in course, and he ascribed it to ignorance of the heavens. And in spite of his (Abu Ma’shār’s) telling the truth, he (Abū Muḫammad) still degrades Abu Ma’shār, and he does not give him his due esteem. For after all Abu Ma’shār does not deserve all this attribution of ignorance, even though he erred in his nomenclature here and followed partially the author of al-Bizīdhaj. (Valens)
5:10-19 p6. Al-Bīrūnī on Transits – A study of an Arabic Treatise entitled Tamhīd al-mustaqarr li-taḫqīq ma´nā al-mamar
By Abū l-Rayḫān al-Bīrūnī
Translated by Mohammad Saffouri & Adnan Ifram
With commentary by Edward S. Kennedy, Institute for the History of Arabic-Islamic Science, At the Johann Wolfgang Goethe University Frankfurt am Main, Islamic Mathematics and Astronomy Volume 33 ©1998
Many thanks to Steven Birchfield for pointing me out the quote.