| Abu Nasr Sa'd | |
| Succession: | Sultan of Granada (1st reign) |
| Reign1: | 1455–1462 |
| Predecessor1: | Muhammad XI of Granada |
| Successor1: | Yusuf V of Granada |
| Succession2: | Sultan of Granada (2nd reign) |
| Reign2: | 1463–1464 |
| Predecessor2: | Yusuf V of Granada |
| Successor2: | Abu'l-Hasan Ali of Granada |
| House: | Nasrides |
| House-Type: | Dynasty |
| Birth Date: | Unknown |
| Death Date: | 1465 |
| Religion: | Islam |
Abu Nasr Sa'd ibn Ali ibn Yusuf (Arabic: أبو نصر سعد بن علي بن يوسف|ʾAbū Naṣr Saʿd ibn ʿAlī ibn Yūsuf), known by the regnal name al-Musta'in bi-llah (Arabic: المستعين بالله|al-Mustaʿīn bi-ʾllāh|he who looks for help to God) and as Ciriza (a corruption of Sidi Sa'd) or Mulay Zad ("Lord Sa'd) to the Christian chroniclers, was the twentieth Nasrid ruler of the Moorish Emirate of Granada in Al-Andalus on the Iberian Peninsula.
. L. P. Harvey. Islamic Spain, 1250 to 1500. 1990. University of Chicago Press. Chicago. 978-0-226-31962-9.