The statement of al-Mughīrah ibn Shuʿbah: "It is sufficient for you to say, 'Seal of the Prophets' …"
Mujālid ibn Saʿīd has been considered weak by some scholars and trustworthy by others, while the rest of the narrators are reliable. - Majma al-Zawaid wa-manba al-Fawaid

Majma al-Zawaid wa-manba al-Fawaid cover - al-Haythami
Al-Mughīrah ibn Shuʿbah - Seal of the Prophets, Majma al-Zawaid (al-Haythami) part 1
Al-Mughīrah ibn Shuʿbah - Seal of the Prophets, Majma al-Zawaid (al-Haythami) part 2