It was narrated from Miqdad bin Aswad that:
He asked the Prophet about a man who approached his wife, but did not ejaculate. He said: "If anyone of you finds that, he should sprinkle water over his private part (meaning he must wash it) and perform ablution."

حَدَّثَنَا مُحَمَّدُ بْنُ بَشَّارٍ، حَدَّثَنَا عُثْمَانُ بْنُ عُمَرَ، حَدَّثَنَا مَالِكُ بْنُ أَنَسٍ، عَنْ سَالِمٍ أَبِي النَّضْرِ، عَنْ سُلَيْمَانَ بْنِ يَسَارٍ، عَنِ الْمِقْدَادِ بْنِ الأَسْوَدِ، أَنَّهُ سَأَلَ النَّبِيَّ ﷺ عَنِ الرَّجُلِ يَدْنُو مِنِ امْرَأَتِهِ فَلاَ يُنْزِلُ قَالَ " إِذَا وَجَدَ أَحَدُكُمْ ذَلِكَ فَلْيَنْضِحْ فَرْجَهُ - يَعْنِي لِيَغْسِلْهُ - وَيَتَوَضَّأْ " .