Khutbah.
Referring to the Israelites in Surah Al-Baqarah, Allah stresses that like them, we are in real danger that our hearts will harden even though the Quran is in our hands and we recite it in prayer. In the same surah, Allah teaches us how to protect our hearts from this, first by maintaining a deep connection with our creator, which in turn will improve our relationships with close family; then by always speaking well of people, followed by establishing the prayer and finally giving zakat. Salat is the means by which our worship of Allah and goodness to others is reinforced. The consequences of a hardened heart are grave, leading to a strong warning from Allah in ayah 85 against those who believe in some parts of His book and choose to deny or ignore others, if it doesn't serve their interests. The compensation for such extremists on both sides (those obsessed with the superficial aspects of religion or those who fail to observe even the most basic rites) is humiliation in this life and the worst of jahannam in the afterlife. Such behavior damages the Ummah at large because it makes Islam itself appear contradictory.