صحيح البخاري Sahih Bukhari كتاب الأحكام The Book of Al-Ahkam (Judgements)
بَابُ مَا يُكْرَهُ مِنْ ثَنَاءِ السُّلْطَانِ، وَإِذَا خَرَجَ قَالَ غَيْرَ ذَلِكَ:

(27) Chapter. What is disliked as regards praising the Sultan (ruler) (in his presence) and saying something differently after leaving him.

2 hadith
Hadith 7178
حَدَّثَنَا أَبُو نُعَيْمٍ ، حَدَّثَنَا عَاصِمُ بْنُ مُحَمَّدِ بْنِ زَيْدِ بْنِ عَبْدِ اللَّهِ بْنِ عُمَرَ ، عَنْ أَبِيهِ ، قَالَ أُنَاسٌ لِابْنِ عُمَرَ : إِنَّا نَدْخُلُ عَلَى سُلْطَانِنَا ، فَنَقُولُ لَهُمْ خِلَافَ مَا نَتَكَلَّمُ إِذَا خَرَجْنَا مِنْ عِنْدِهِمْ ، قَالَ : " كُنَّا نَعُدُّهَا نِفَاقًا " .
Narrated Muhammad bin Zaid bin `Abdullah bin `Umar: Some people said to Ibn `Umar, "When we enter upon our ruler(s) we say in their praise what is contrary to what we say when we leave them." Ibn `Umar said, "We used to consider this as hypocrisy."
Hadith Reference Sahih Bukhari / The Book of Al-Ahkam (Judgements) / Hadith: 7178
Hadith Grading محدثین: أحاديث صحيح البخاريّ كلّها صحيحة
Hadith 7179
حَدَّثَنَا قُتَيْبَةُ ، حَدَّثَنَا اللَّيْثُ ، عَنْ يَزِيدَ بْنِ أَبِي حَبِيبٍ ، عَنْ عِرَاكٍ ، عَنْ أَبِي هُرَيْرَةَ ، أَنَّهُ سَمِعَ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ ، يَقُولُ : "إِنَّ شَرَّ النَّاسِ ذُو الْوَجْهَيْنِ ، الَّذِي يَأْتِي هَؤُلَاءِ بِوَجْهٍ وَهَؤُلَاءِ بِوَجْهٍ " .
Narrated Abu Huraira: Allah's Apostles said, "The worst of all mankind is the double-faced one, who comes to some people with one countenance and to others, with another countenance."
Hadith Reference Sahih Bukhari / The Book of Al-Ahkam (Judgements) / Hadith: 7179
Hadith Grading محدثین: أحاديث صحيح البخاريّ كلّها صحيحة