Charles Spurgeon Commentary 1 John 2:24

"As for you, let that abide in you which ye heard from the beginning. If that which ye heard from the beginning abide in you, ye also shall abide in the Son, and in the Father." — 1 John 2:24 (ASV)

Let that therefore abide in you, which ye have heard from the beginning. If that which ye have heard from the beginning shall remain in you, ye also shall continue in the Son, and in the Father.

Since it was the truth that was revealed to them at first, there was no need for a later revelation to correct the mistakes of the first, as some foolishly and falsely teach nowadays.