What is the ruling on delaying the slaughter of a vowed sheep due to inability, and is expiation for an oath permissible in its place?

The summary of fatwas concerning vows is that if it is possible to fulfill the vow, then fulfilling it becomes obligatory, even if it is after a period, unless a specific time was designated. If a person is completely unable to fulfill the vow, then he must offer expiation for an oath (kaffarat yamin). As for misfortunes occurring in this world due to not fulfilling a vow, there is no text in the Quran or Sunnah that states this. However, it is considered among the sins for which a servant may be punished in this world and the hereafter, unless Allah forgives him, as Allah Almighty says: "And whatever strikes you of disaster - it is for what your hands have earned; and He pardons much." (Ash-Shura: 30).