Because the swallow loved the prince and after losing both the sapphires the prince had gone blind. So the swallow started telling the prince whatever he saw in the city daily. :)

Introduction:
In the story "The Happy Prince" by Oscar Wilde, the swallow and the prince form a unique friendship. The swallow, initially intending to fly to Egypt, decides to stay with the prince instead. This decision by the swallow is influenced by several factors.

1. Compassion and Empathy:
The swallow is portrayed as a compassionate and empathetic character throughout the story. When he first encounters the prince, he notices the statue's sadness and suffering. This compassion drives the swallow to help alleviate the prince's pain. He chooses to stay and assist the prince in his mission to help the poor and needy.

2. Sense of Duty and Loyalty:
The swallow demonstrates a strong sense of duty and loyalty towards the prince. He acknowledges the prince's selflessness and genuine concern for the less fortunate. The swallow recognizes that by staying with the prince, he can contribute to the welfare of others. His loyalty towards the prince and his mission outweighs his initial plan of going to Egypt.

3. Sacrifice and Selflessness:
The swallow's decision to stay with the prince also reflects his willingness to sacrifice his own desires for the greater good. By giving up his migration to Egypt, the swallow puts the prince's needs above his own. This selfless act highlights the depth of their friendship and the swallow's commitment to making a positive impact on the world.

4. Transformation and Growth:
Throughout the story, the swallow undergoes a transformation. Initially, he is focused on his own comfort and survival. However, as he spends time with the prince, he begins to understand the true meaning of love, compassion, and selflessness. This growth in character leads to his decision to stay and help the prince, rather than pursuing his personal desires.

Conclusion:
The swallow's decision to stay with the prince instead of going to Egypt is influenced by his compassion, sense of duty, loyalty, sacrifice, and personal growth. Through their friendship and shared mission, both the swallow and the prince learn valuable lessons about empathy, kindness, and the importance of helping others.