Sayyiduna Ubayy bin Ka'b (may Allah be pleased with him) narrates: The Prophet (peace and blessings be upon him) said: "O Bilal, make enough of a pause between your adhan and your iqamah that one who is eating can finish his food at ease, and one who is making ablution can relieve himself at ease."
Abdullah bin Ahmad recorded it in his "Ziyadat" as a narration of Abu al-Jawza' from Sayyiduna Ubayy (may Allah be pleased with him), and Abu al-Jawza' did not hear from Sayyiduna Ubayy.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الصلاة / 1917