Key signs include improved character, increased devotion to shalat, avoidance of previous sins, greater humility, and increased charity — Nabi said Haji Mabroor's reward is Paradise.
The scholars have identified that the primary sign of an accepted Haji is a positive transformation in the jamaah haji's character and worship after returning home. Nabi (shallallahu alaihi wa sallam) said: 'An accepted Haji has no reward except Paradise' (Bukhari and Muslim). While only Allah knows with certainty whether a Haji is accepted, scholars point to several encouraging indicators.
These signs include: the jamaah haji feels a greater closeness to Allah and increased love for worship, they maintain or increase their devotion to the five daily shalat, they exhibit more patience, humility, and kindness in their dealings with others, they actively avoid sins they may have been involved in before Haji, they increase in charitable giving and good deeds, and they feel a longing to return to the holy sites. The absence of boasting about the ibadah haji is itself considered a positive sign, as sincerity is the foundation of accepted worship.
Source: Sahih al-Bukhari, Kitab al-Haji; Sahih Muslim, Kitab al-Haji