Jamieson, Fausset and Brown on 1 Timothy 6:7

7. For--confirming the reasonableness of "contentment."

and it is certain--Vulgate and other old versions support this reading. The oldest manuscripts, however, omit "and it is certain"; then the translation will be, "We brought nothing into the world (to teach us to remember) that neither can we carry anything out" (Job 1:21; Ec 5:15). Therefore, we should have no gain-seeking anxiety, the breeder of discontent (Mt 6:25).