Does rinsing after ablution for prayer nullify the ablution, necessitating its repetition?

The emission of urine invalidates ablution (wudu'), whether or not the person cleanses himself (istinja'). Similarly, touching the private parts (front or back) invalidates ablution. Ablution is not valid before istinja' according to many jurists, who cite the hadith of Al-Miqdad: "He washes his private parts and then performs ablution." Others believe in the validity of ablution before it, provided he does not touch his private parts. The Sunnah is to perform istinja' before ablution.