Explanation

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.