It is narrated from Sayyiduna Anas bin Malik (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "If I were to swear an oath, I would surely be true (in my oath): the most beloved of Allah's servants to Allah are those who watch over the sun and the moon" - meaning the mu'adhdhins (callers to prayer) - "and they will indeed be recognized on the Day of Resurrection by the length of their necks."
Hadith Referenceالمعجم الأوسط / باب العين / 4808
Hadith Gradingمحدثین:إسناده ضعيف جدًّا، فيه جنادة بن مروان متهم
Hadith Takhrij«قال الهيثمي: فيه جنادة بن مروان قال الذهبي اتهمه أبو حاتم «مجمع الزوائد ومنبع الفوائد، ج 1، ص 326»» «أخرجه أحمد فى «مسنده» برقم: 12926، 13997، والبزار فى «مسنده» برقم: 7564»