History of the Peloponnesian War
Thucydides
Thucydides. The history of the Peloponnesian War, Volume 1-2. Dale, Henry, translator. London: Heinemann and Henry G. Bohn, 1851-1852.
The majority therefore, through fear, were eager to conclude the alliance with the Argives on their own part, respectively, as the Mantineans had done.
When the Lacedaemonians perceived this commotion which had arisen in the Peloponnese, and that the Corinthians were the advisers of it, and were themselves about to enter into treaty with Argos, they sent ambassadors to Corinth, wishing to prevent what was going to happen. They charged them therefore with suggesting the whole business; and said that if they withdrew from them, and became allies of the Argives, they would violate their oaths; and that they were already doing wrong in not accepting the treaty with the Athenians, when it had been declared, that whatever the majority of the allies decreed, should be binding, unless there were some impediment on the part of gods or heroes.