It was narrated that Anas bin Malik said: “Ramadan began, and the Messenger of Allah (ﷺ) said: ‘This month has come to you, and in it there is a night that is better than a thousand months. Whoever is deprived of it is deprived of all goodness, and no one is deprived of its goodness except one who is truly deprived.’”
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا أَبُو بَدْرٍ، عَبَّادُ بْنُ الْوَلِيدِ حَدَّثَنَا مُحَمَّدُ بْنُ بِلاَلٍ، حَدَّثَنَا عِمْرَانُ الْقَطَّانُ، عَنْ قَتَادَةَ، عَنْ أَنَسِ بْنِ مَالِكٍ، قَالَ: دَخَلَ رَمَضَانُ. فَقَالَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ " إِنَّ هَذَا الشَّهْرَ قَدْ حَضَرَكُمْ وَفِيهِ لَيْلَةٌ خَيْرٌ مِنْ أَلْفِ شَهْرٍ مَنْ حُرِمَهَا فَقَدْ حُرِمَ الْخَيْرَ كُلَّهُ وَلاَ يُحْرَمُ خَيْرَهَا إِلاَّ مَحْرُومٌ " .
sunnah.com