"I heard my father say: 'I entered upon 'Aishah, and I heard her say: "When the Messenger of Allah exited the toilet, he would say: Ghufranaka (I seek Your forgiveness).'" (Sahih) Another chain with similar wording.
سَمِعْتُ أَبِي يَقُولُ دَخَلْتُ عَلَى عَائِشَةَ فَسَمِعْتُهَا تَقُولُ كَانَ رَسُولُ اللَّهِ ﷺ إِذَا خَرَجَ مِنَ الْغَائِطِ قَالَ غُفْرَانَكَ قَالَ أَبُو الْحَسَنِ بْنُ سَلَمَةَ وَأَخْبَرَنَا أَبُو حَاتِمٍ حَدَّثَنَا أَبُو غَسَّانَ النَّهْدِيُّ حَدَّثَنَا إِسْرَائِيلُ نَحْوَهُ
[Machine] "I entered upon Aisha and heard her saying, 'The Messenger of Allah ﷺ used to say 'Your forgiveness' when he came out of the toilet.'"
دَخَلْتُ عَلَى عَائِشَةَ فَسَمِعْتُهَا تَقُولُ كَانَ رَسُولُ اللَّهِ ﷺ إِذَا خَرَجَ مِنَ الْغَائِطِ قَالَ «غُفْرَانَكَ»
[Machine] "I heard my father say, 'I entered upon Aisha and heard her say that when the Messenger of Allah ﷺ would come out of the restroom, he would say: "I seek your forgiveness."'
سَمِعْتُ أَبِي يَقُولُ دَخَلْتُ عَلَى عَائِشَةَ فَسَمِعْتُهَا تَقُولُ كَانَ رَسُولُ اللَّهِ ﷺ إِذَا خَرَجَ مِنَ الْخَلَاءِ قَالَ «غُفْرَانَكَ»