Is it permissible to be released from a vow that was declared openly, and can this release be delayed due to lack of funds?

Whoever makes a vow is obligated to fulfill it. If he is unable to fulfill it due to lack of money or other reasons, then he must offer expiation for breaking an oath. The proof for this is the saying of the Prophet, peace and blessings be upon him: "Whoever makes a vow and does not specify it, its expiation is the expiation of an oath. And whoever makes a vow he cannot fulfill, its expiation is the expiation of an oath."