What is the significance of Salatul-Istikhara (the Prayer of Seeking Guidance), and what is its benefit in relation to divine decree and destiny (Al-Qada wal-Qadar)?

The importance of Salatul-Istikhara lies in three aspects: First, it embodies the realization of Tawhid (monotheism), entrusting affairs to Allah, and relying upon Him. Second, it leads to success in choice and divine guidance in the matter for one who entrusts their affair to Allah and sincerely asks Him. Third, it cultivates contentment with divine decree and satisfaction with what has been apportioned. Whoever performs Istikhara to Allah will not regret their choice. The most hated of Allah's servants, according to Dawud (peace be upon him), is one who performs Istikhara to Allah and then is not content with His decree. Istikhara combines Tawhid, servitude, and reliance upon Allah, and it is a sign of happiness and contentment with Allah's decree, whereas abandoning it is a sign of wretchedness.