Is delaying prayer by half an hour or a quarter of an hour after the Adhan without a valid excuse considered a sin?

The most beloved deeds to Allah are: performing prayers on time, then honoring one's parents, then striving in the way of Allah.

Hastening to prayer at the beginning of its time is better than delaying it, though delaying the prayer as long as it is within its prescribed time does no harm.

Whoever catches one rak'ah before the time expires has caught the prayer.

Delaying the prayer by a quarter or half an hour after the adhan, but before its time expires, carries no sin. Sin occurs when the prayer is delayed until its time expires, in fulfillment of Allah's saying: (So woe to those who pray [But] who are heedless of their prayer).