Law kaana 'aradan qareebanw wa safaran qaasidal lattaba'ooka wa laakim ba'udat 'alaihimush shuqqah; wa sayahlifoona billaahi lawis tata'naa lakharajnaa ma'akum; yuhlikoona anfusahum wal laahu ya'lamu innahum lakaa ziboon
Had it been a near [i.e., easy] gain and a moderate trip, they [i.e., the hypocrites] would have followed you, but distant to them was the journey. And they will swear by Allah, "If we were able, we would have gone forth with you," destroying themselves [through false oaths], and Allah knows that indeed they are liars.
1 Mufti Taqi Usmani
Had it been a gain at hand or an average journey, they would have certainly followed you, but the distance seemed too far to them. They will swear by Allah: “We would have certainly set out with you, if we were able to.” They are putting themselves to ruin.16 Allah knows that they are liars.