Reference for Moed Katan 39:17
איני והא רב בר אחוה דרבי חייא דהוא בר אחתיה דר' חייא כי סליק להתם אמר ליה אבא קיים
but for one's father or mother [mourning is for] seven [days] and [up to] thirty [days] - [Raba] replied: That is the ruling of an individual<span class="x" onmousemove="('comment',' The authority is named lower down.');"><sup>24</sup></span> with which we do not concur, as [will be made clear from what] is taught [in the following]: 'There was the case of the father of R'Zadok who had died at Ginzak,<span class="x" onmousemove="('comment',' Gazaka, a city in North Media (Atropatene) ; according to Rawlinson it is Shiz near Lake Urmia. V. Obermeyer p. 10.');"><sup>25</sup></span> and he was not informed till after three years. He [thereupon] came and asked of Elisha B'Abuyah and the elders that were with him and they told him to observe seven [days] and [up to] thirty, and when R'Ahiyya's son died in the Diaspora,<span class="x" onmousemove="('comment',' Golah, the ancient place of the 'Captivity' when the first Temple fell, Babylon, Nehardea and later, Pumbeditha, were considered the most ancient centres of the Golah.');"><sup>26</sup></span> he [too] sat on his account seven and [observed mourning up to] thirty'. But this is not so? For when Rab, R'Hiyya's brother's son - who was also R'Hiyya's sister s son<span class="x" onmousemove="('comment',' R. Aha of Kafri married a widow and his eldest son Aybu married her daughter. From these unions Aha had a son R. Hiyya, and Aybu had a son Rab ('R. Abba the Long', later the famous principal of Sura) . Rab's mother was R. Hiyya's half-sister (from one mother, i.e., R. Ala's second wife) ; and Rab's father Aybu was R. Hiyya's eldest half-brother (from the same father, namely, R. Aha of Kafri) . R. Hiyya was therefore doubly related to his nephew Rab, being his paternal uncle as well as his maternal uncle, cf. Pes. ');"><sup>27</sup></span> - came up there [to Palestine], he [R'Hiyya] said to his nephew [Rab]: 'Is father alive'?<span class="x" onmousemove="('comment',' I.e., is my father Aha alive?');"><sup>28</sup></span>