Is it obligatory to perform ablution after every urination or defecation outside of prayer times, and is there any narration indicating that?

There is no evidence that ablution (wudu') is obligatory after every impurity (hadath) unless the Muslim intends to pray, as Allah Almighty says: (O you who have believed, when you rise to [perform] prayer...). This is further indicated by the Prophet, peace and blessings be upon him, exiting the lavatory and then saying, when food was brought near him, "I was commanded to perform ablution only when I rise for prayer." It is permissible for a Muslim to pray with a single ablution as long as he does not invalidate it. It has been authentically reported that the Prophet, peace and blessings be upon him, prayed all the prayers on the day of the conquest of Mecca with a single ablution.