Sounds to me like "de bottom haff fi drop out" (has to drop out) here. cf. "de bucket bottom mus' drop out" ( = will drop out) and Phil's other possibility ( = is going to drop out).

Funny enough, this is the Wailers in their let's-appeal-to-Rock-audiences phase and with British production bringing them closer to the Anglo audience, and there is almost no patois in it—it just barely sneaks in for the familiar proverb.

As a deep Jamaican music listener, who might otherwise be inclined to rake covers by non-Jamaicans over the coals, I feel Clapton's cover is not a disaster but rather is not far off from and, in some ways, actually feels more aligned with Jamaican music style (be it as it often includes Black American musical style) than The Wailers' slightly odd sounding performance. Not sure if it was because they had Marley and Tosh playing guitars (rather than Reggie Lewis) or because they were possibly augmented (as on _Catch a Fire_) by some English studio musicians. I'm not saying that's bad, just remarking on the idiosyncratic sound of this song/album. The irony is that The Wailers, for many, became a model for Jamaican music sound, so it's a matter of interest (to me at least) when in cases like their sound actually wasn't representative.