Sayyiduna Abu al-Darda (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) said: "Everything has a beginning, and the beginning of the prayer is the first takbir, so guard it." Abu Abdullah said: I narrated this report to Raja bin Haywah, and he said: Sayyidah Umm al-Darda (may Allah be pleased with her) narrated this hadith to me from Sayyiduna Abu al-Darda (may Allah be pleased with him), from the Prophet (peace and blessings be upon him).
Al-Bazzar recorded it, and al-Tabarani recorded something similar in al-Mu'jam al-Kabir as a mawquf report; its chain contains a narrator who is not named.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الصلاة / 2599