The one who deliberately abandons the prayer is liable to execution:
“I have been commanded to fight the people until they bear witness that there is no god but Allah and that Muhammad is the Messenger of Allah, establish the prayer, and pay the zakah. When they do so…” – the ḥadith is agreed upon by al-Bukhārī and Muslim.
“There will be rulers set over you; you will approve of some of what they do and disapprove of some. Whoever rejects their wrong is absolved, and whoever detests it is safe, but whoever is content with it and follows them…” They asked, “Shall we not fight them?” He replied, “No, not as long as they pray.” Reported by Muslim.
“It is said of him, ‘Does he not pray?’ He replied, ‘Indeed he does, yet he truly has no prayer.’”
The Prophet ﷺ also said, “They are the ones whom Allah has forbidden me to kill.” Reported by Mālik (1/185) as a mursal narration with a sound chain; al-Shāfiʿī and Aḥmad connected the chain in their Musnads.
A corroborating report comes from Anas, related by al-Ṭabarānī, Abū Yaʿlā, and al-Bazzār (Majmaʿ, 1/296), and another from Abū Hurayrah (Abū Dāwūd, 2/305).

Prayer is not obligatory for a minor until he reaches puberty:
“The pen has been lifted from three: from the sleeper until he awakes, from the child until he reaches puberty, and from the insane until he regains his reason.” Reported by Abū Dāwūd, al-Nasāʾī, al-Tirmidhī, Ibn Mājah, al-Mundhirī, Muslim, and Aḥmad (6/100–101). Taken together with its various routes and corroborating narrations, the report is authentic. See Naṣb al-Rāyah (4/161–165), Talkhīṣ al-Ḥabīr (2/95–96), and Miftāḥ Kunūz al-Sunnah, p. 152.

Nevertheless, the guardian must command the child to pray at seven years of age and discipline him for neglecting it at ten:
“Command your children to pray when they are seven years old, and strike them for [leaving] it when they are ten…”