Ibn al-Mubarak (may Allah have mercy on him) said: In this hadith there is no strength for the one who says that when the imam leads the prayer without ablution (wudu), his companions are to repeat the prayer; and the other hadith, that the people do not repeat the prayer, is better established. This is for the one who seeks fairness through the hadith.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4081