Abu Dawud Book 14, Hadith Number 3178.

Narated By Abdullah ibn Mas’ud : We asked the Prophet (PBUH) about walking with the funeral. He replied: Not running (but walking quickly). If he (the dead person) was good, send him to it quickly; if he was otherwise, keep away the people of Hell. The bier should be followed and should not follow. Those who go in front of it are not accompanying it.