Musannaf Ibn Abi Shayba 28:326

Ibn ‘Uyaynah narrated to us, from Muhammad ibn Suqah, who said: A man asked ‘Ata’ about a man whom the Daylam had captured, and they took from him the covenant of Allah and His solemn pledge that he would send [something] to them. [The man asked]: "If he sends to them after he has ransomed himself, then he is free [of the obligation], but if he does not send to them, the covenant and the solemn pledge are upon him to return to them." He [the man] could not find [the means to pay], and he was in financial hardship. He said—meaning regarding the covenant—and he said: "They are people of shirk." But ‘Ata’ refused [to accept anything] except that he must fulfill the covenant.