The scripture means the statement of liberated holy man.
We have to test everything from three positions: the spiritual master, scripture, and holy man. Scripture means, just like Bible. What is Bible? Scripture. Why the scripture? It is fully contains the instruction of sadhu, holy man, or spiritual master, Lord Jesus Christ, therefore is scripture. The scripture means the statement of liberated holy man. That is sadhu. Therefore, scripture should be tested through the holy man and spiritual master. Spiritual master should be tested through scripture and holy man, and holy man should be tested through spiritual master and scripture.
[S.P. Room Conversation with Allen Ginsberg, May 11, 1969, Columbus, Ohio]
Note: So Prabhupada's lectures, letters, conversations and his authorized autobiography [Srila Prabhupada Lilamrta As It Is] are also scripture.
The ten offenses against the holy name are as follows: (4) to minimize the authority of scriptures (Vedas) [C.C. Adi lia 7.73]
Note: It is also interesting to note that statements like the following by Narayana Maharaja are offensive minimizations of the authority of Prabhupada's letters [scripture]
[Gokula dasa:] Actually, within ISKCON there was two or three. [Letters about originally being with Krishna]

[Srila Narayana Maharaja:] I know. I have read them. Srila Swami Maharaja sometimes gave baby food to babies. When I give a baby medicine like quinine, I tell him, "Baby, baby, it is very sweet." I'm telling him something that is not true so that I can give him the medicine. Similarly, Srila Swami Maharaja has written to someone who was very low in bhakti. A letter cannot always be proof. What Srila Swami Maharaja has written in Caitanya-caritamrta and in his Gita and Bhagavata explanation is authentic. These are proofs. He can write something else for a little baby, but it is not proof.