Al-A'mash narrated from Sayyiduna Anas (may Allah be pleased with him). The narrator says: I think he narrated it as marfu' (attributed to the Prophet). He (peace and blessings be upon him) said: "The mu'adhdhins will be the people with the longest necks on the Day of Resurrection."
Al-Bazzar recorded it; al-A'mash did not hear from Sayyiduna Anas (may Allah be pleased with him).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الصلاة / 1839