Al-Matalib al-'Aliyah 3638 — Surah Yusuf

It is narrated from Sa'id bin Jubayr (may Allah have mercy on him) concerning this saying of Allah Almighty: "the king's measuring cup (suwa')" [Surah Yusuf: 72], that he said: "What is meant is the Persian measure or cup called al-makkuk al-farisi. It is the very vessel from which the non-Arabs used to drink, and its shape is such that its two ends meet each other (in a curve)."
Sunan Abi Dawud: 3638. Allamah al-Albani declared the chain of this report sahih (authentic).