Grading: Its narrators are thiqah,
Technical note / Defect ('illah): but narrators other than Hammad bin Salamah narrated it from Yunus (who is Ibn 'Ubayd) and said: "Yusuf (peace be upon him) was thrown into the well when he was seventeen (17) years old." Likewise al-Mubarak bin Fadalah narrated it from al-Hasan al-Basri. (Clarifying the kunyah): Abu 'Abdullah al-Hafiz is Muhammad bin Ya'qub al-Akhram.

Reference / Source: Ibn Abi Shaybah 11/ 564 and 13/ 61, Imam Ahmad in "al-Zuhd" (421) and "al-'Ilal" (3798), al-Tabari in his "Tafsir" 13/ 71, Ibn Abi Hatim in "al-Tafsir" 7/ 2202, and Abu Bakr al-Dinawari in "al-Mujalasah" (2802) narrated it by way of Isma'il Ibn 'Ulayyah. Ibn 'Abd al-Hakam in "Futuh Misr" (p.) and al-Tabari in his Tafsir 13/ 71 and Tarikh 1/ 363 narrated it by way of 'Abd al-Wahid bin Ziyad, and al-Tabari in his "Tafsir" 13/ 71 by way of Hushaym bin Bashir.
Details of the narration: All three (Isma'il, 'Abd al-Wahid and Hushaym) narrate it from Yunus, from al-Hasan (al-Basri), that: "Yusuf (peace be upon him) was thrown into the well when he was seventeen (17) years old …"

Reference / Source: Likewise Adam bin Abi Iyas narrated it in his "Tafsir" 1/ 321 (which was printed under the name "Tafsir Mujahid", though it is by Adam bin Abi Iyas and not by Mujahid), and al-Tabari in his "Tafsir" 13/ 71 and "Tarikh" 1/ 363, by way of al-Mubarak bin Fadalah, from al-Hasan (al-Basri).