Sunan at-Tirmithiy كتاب الطهارة باب ما جاء أن الماء من الماء

حَدَّثَنَا أَحْمَدُ بْنُ مَنِيعٍ حَدَّثَنَا عَبْدُ اللَّهِ بْنُ الْمُبَارَكِ أَخْبَرَنَا يُونُسُ بْنُ يَزِيدَ عَنِ الزُّهْرِىِّ عَنْ سَهْلِ بْنِ سَعْدٍ عَنْ أُبَىِّ بْنِ كَعْبٍ قَالَ إِنَّمَا كَانَ الْمَاءُ مِنَ الْمَاءِ رُخْصَةً فِى أَوَّلِ الإِسْلاَمِ ثُمَّ نُهِىَ عَنْهَا.
Indeed, "water (ritual washing) is obligatory after water (ejaculation)", was only a mitigation in the early days of Islam, then it became forbidden. (1) Footnote: (1) It was abrogated, and (ritual) washing became obligatory when sexual intercourse occurs, even with no ejaculation.