It is narrated from Tawus bin Kaysan (may Allah have mercy on him) that on the day of the Battle of the Trench the Messenger of Allah (peace and blessings be upon him) said: 'Allahumma la 'aysha illa 'ayshu al-akhirah, fa-rhami al-Ansara wa al-Muhajirah, wa-l'an 'Adalan wa al-Qarah, hum kallafuna naqla al-hijarah' (O Allah, the true life is only the life of the Hereafter, so send Your mercy upon the Ansar and the Muhajirun; and curse Adal and al-Qarah (the tribes so named), for they have burdened us with carrying stones (that is, digging the trench and the hard labour of defence)).
This narration is mursal, because Imam Tawus (may Allah have mercy on him) is a Successor (Tabi'i) and he is narrating directly from the Prophet (peace and blessings be upon him).
Hadith Referenceالمطالب العالية بزوائد المسانيد الثمانية / كتاب السيرة والمغازي / 4275
Hadith Gradingمحدثین:إسناده ضعيف جدًا، مرسل
Hadith Takhrij«حکم الحدیث المطالب العالیہ محققاً تنسیق د. سعد بن ناصر بن عبد العزيز الشَّثري- مکتبہ شاملہ :مرسل، إسناده ضعيف جدًا. » «أخرجه مصنف عبد الرزاق برقم: 19912»