Explanation:

According to Puratan Janamsakhi, before Guru Nanak turned towards east, he went to Tolumba (now known as Makadampur in west Pakistan) and met Sajjan Thug. Sajjan always wore a white dress, displayed his rosary and thus posed to be a holyman. He had built a Hindu temple and a Muslim mosque at the courtyard of his residence. He would invite wayfarers to his residence to rest for the night. But at night, he would take away their goods and money and sometimes kill them. The Guru went and stayed with him for the night. At night the Guru did not go to bed early which made Sajjan a bit too nervous to perform his nefarious act of robbing. Sajjan asked the Guru to take rest and sleep but the Guru replied,"God's minstrel does not go to sleep, till God sends word that he should retire.