Anas ibn Mālik (may Allah be pleased with him) reported that the Prophet (may Allah's peace and blessings be upon him) said: ''Praise be to Allah Who gave us food and drink, provided for us sufficiently, and gave us shelter, for how many there are who have no one to provide for them or to give them shelter.''
When the Prophet (may Allah's peace and blessings be upon him) went to bed, he would say this Dhikr in which he would thank Allah for providing him with food and drink. Were it not for Allah, the Almighty,, one would not have access to food and drink, so praise is due to Allah for that. Also, the Prophet would thank Allah for facilitating matters for him, securing him provisions, as well as giving him a place to shelter him, given that many people have no means of sustenance or shelter. So, it is recommended to say this Dhikr when going to bed.