Abraham ben Jacob (Hebrew: ?, Abraham ben Jacob; fl. 961-62; also Arabic: ? sometimes Ibrâhîm ibn Ya`qûb al-Tartushi or al-?ur?ûshî) was a tenth-century Hispano-Arabic, Sephardi Jewish traveller, probably a merchant, who may have also engaged in diplomacy and espionage.
His family hailed from Moorish-ruled ?urah (now Tortosa) close to the mouth of the Ebro: he may also have lived in Córdoba. Written and oral history and his writings suggest that he had a Jewish background. However, it has also been argued by other historians that he was a Muslim of Jewish background, and Bernard Lewis states: "There is some uncertainty to whether he was a professing Jew or a Muslim of Jewish origin."
Nothing is known about his return to al-Andalus (the Muslim-ruled part of the Iberian Peninsula), nor of any further travel. The memoirs and commentaries of his journey, possibly first presented to the Cordoban caliph Al-Hakam II (961-76), have been lost; only excerpts by later authors have been preserved, principally Abu Abdullah al-Bakri's Book of Highways and of Kingdoms and the work of Zakariya al-Qazwini, possibly via the writings of Al-Udri.
His work is widely known as providing the first reliable description of the Polish state under Mieszko I, the first historical ruler of Poland. He is also noted for his description of the Vikings living in Hedeby; of the Nakonid fortification at Mecklenburg Castle; and of what was, in all likelihood, the nucleus of the later ducal castle and palace at Schwerin. Ibrahim ibn Yaqub has a unique place in Czech history as the first person to mention the city of Prague and its Jewish community in writing. He also mentioned Czech Boleslaus I, Duke of Bohemia and Krakow as part of Duchy of Bohemia.