Al-Matalib al-'Aliyah 507 — Ruku, sujud and the remembrance in them

It is narrated from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) that he said: "On a rainy day I saw the Messenger of Allah (peace and blessings be upon him) (in prayer) protecting himself (from the wetness and mud of the ground) with a cloak, and the situation was that when he (peace and blessings be upon him) prostrated, there was mud on that cloak."
Abu Ya'la al-Mawsili recorded this hadith in his Musnad. Its chain contains Husayn bin Abdullah bin Ubaydullah bin Abbas, whom the majority of hadith scholars graded da'if (weak); however, the meaning of performing the prayer with care in rainy conditions is also clear from other authentic reports.