For someone (agent) to plant his foot (theme i-) or feet solidly on something (loc ref), as on the bed of a river when helping someone across a rushing stream, on a slippery rock so one will not slip.
Immuy amih wangwang ya alyon ta idah'ay'uh din batu ya nida'lēha' ti mundangngol.
We went to the river and (I) thought that I had planted (my foot) on that stone and I slipped because it was slippery.