'Excelling' in the Bible

“Even the stork in the skyKnows her seasons [of migration],And the turtledove, the swallow and the craneObserve the time of their return.But My people do not knowThe law of the Lord.

Therefore, my beloved brothers and sisters, be steadfast, immovable, always excelling in the work of the Lord [always doing your best and doing more than is needed], being continually aware that your labor [even to the point of exhaustion] in the Lord is not futile nor wasted [it is never without purpose].