In the Name of God, the Most Compassionate, the Most Merciful
Hadiths
Narrations whose displayed text and sources have been rechecked
The translations are intentionally kept as close as possible to the Arabic text displayed.
Narrated by: Umar ibn al-Khattab, from the Prophet Muhammad
Actions are by intentions
إِنَّمَا الأَعْمَالُ بِالنِّيَّاتِ، وَإِنَّمَا لِكُلِّ امْرِئٍ مَا نَوَى
Actions are only by intentions, and every person has what he intended.
Sources: Sahih al-Bukhari 1, narrated by Umar ibn al-Khattab; the same Prophetic wording is also transmitted in Shia collections including Wasa'il al-Shia.
Narrated by: Abu Huraira, from the Prophet Muhammad
Speak good or remain silent
مَنْ كَانَ يُؤْمِنُ بِاللَّهِ وَالْيَوْمِ الآخِرِ فَلْيَقُلْ خَيْرًا أَوْ لِيَسْكُتْ
Whoever believes in God and the Last Day should speak good or remain silent.
Sources: Sahih al-Bukhari 6018/6475 and Sahih Muslim 47, from Abu Huraira; al-Kafi, vol. 2, p. 667 also transmits «فليقل خيراً أو ليسكت».
Narrated by: Zayd ibn Arqam, from the Prophet Muhammad
The Two Weighty Things (al-Thaqalayn)
إِنِّي تَارِكٌ فِيكُمُ الثَّقَلَيْنِ: كِتَابَ اللَّهِ وَأَهْلَ بَيْتِي
I am leaving among you the two weighty things: the Book of God and my Ahl al-Bayt.
Sources: al-Hakim's al-Mustadrak, narration of Zayd ibn Arqam; fuller related wordings also appear in Jami al-Tirmidhi 3788 and other Sunni and Imami sources.