As for the hypocrites, if the gain would have been immediate and the journey short, they would have certainly accompanied you, but the long journey (in Tabuk expedition) was too hard for them. To justify their not accompanying you, they would even swear by Allah, “If we were able, we would certainly have marched with you.” By doing so, they are destroying their own souls, for Allah knows that they are liars.
Meaning:-
Hypocrite: a person who puts on a false appearance of virtue or religion.
Tabuk: The Battle of Tabouk (also called the Battle of Tabuk) was a military expedition, which, was initiated by Muhammad (PBUH) in October, AD 630,8 AH
Expedition: Journey, voyage, tour, a journey or voyage undertaken by a group of people with a particular purpose.