Is one who intentionally, without excuse, abstains from the Tarawih prayer sinful?

Tarawih prayer is a recommended Sunnah, not an obligation. One who omits it does not incur sin, even if done intentionally, but they miss out on a great reward, for the Prophet, peace and blessings be upon him, said: "Whoever stands (in prayer) during Ramadan with faith and expecting Allah’s reward, all his past sins will be forgiven."