Is it possible to retract a vow to pray all the Sunnah prayers if it leads to divine pleasure, and is expiation required for that?

A Muslim should obey Allah without making a vow, so as not to expose himself to hardship or difficulty. The Prophet ﷺ forbade making vows. If a Muslim makes a vow contingent on a condition, he is obligated to fulfill it if the condition is met. However, if the condition is not met, or if he is unsure whether it has been met, he is not obligated to fulfill it, due to the lack of certainty about the condition's fulfillment. This is further supported by the case of a person who doubts whether a divorce contingent on a condition has occurred; if a person doubts whether the condition has been met, the divorce does not take effect. Similarly, if someone makes a vow contingent on Allah being pleased with him, he is not obligated to do anything, because he cannot ascertain whether Allah is pleased or not.