Zevachim 51b (נא:) — the Talmud in English

Give a foundation to the altar of the burnt offering.

For all blood that is placed on the outer altar, its remainder is poured onto its foundation.

And we explain:

If you would think that this is what the verse means,

that the verse came to teach that the remainder of the blood of the ruler's sin offering is poured onto the foundation of the outer altar, this is difficult:

these

remnants—

why do I need a verse concerning the remnants

to say that they are to be placed outside and not inside?

But

the initial placements of the blood of the ruler's sin offering

are performed

outside

for them,

and since the blood was placed outside, why was it necessary to teach us that the remainder is to be poured outside and not inside? If so, it would have been sufficient for the verse to say that the remainder of the blood should be poured “onto the foundation of the altar.” Why do I need the word “burnt offering”? Rather, it teaches you that with regard to all blood placed outside, its remainder is poured onto the foundation of the outer altar.

And if you would say

that the verse is not superfluous for this purpose, because if “the burnt offering” had not been written, we might have thought

to reverse the matter completely,