In your dream, seeing your sister and experiencing feelings both frightening and peaceful can be interpreted in several ways according to Islamic sources.

Key Symbols and Meanings:

1. Sister (أخت - Ukht): The presence of a sibling, especially in a positive light, may indicate companionship, support, or loyalty in your waking life. It could symbolize an aspect of your own personality or life situation that is close to your heart.

2. Frightening and Peaceful Feelings: Experiencing mixed emotions in a dream could signify an internal conflict or a situation in your life that carries both challenges and serenity. It may point towards a need for resolution or balance in your life.

Interpretation:

This dream may be a reflection of your relationship with your sister or someone close to you. The dual emotions of fear and peace might mean that there are elements in this relationship or situation that require attention. Allah might be directing you to consider an area in your life that has potential for growth, transformation, or reconciliation.

Spiritual and Moral Reflections:

• Balance and Reflection (توازن وتأمل): Allah may be encouraging you to seek balance and inner peace despite external challenges. Reflect upon your current circumstances and consider where there might be a need for peace or resolution.

• Communication and Bonding (التواصل والروابط): It might also be a call to enhance your communication and strengthen your bonds with loved ones, ensuring that you approach matters of the heart with sincerity and wisdom.

In any dream that contains mixed feelings, it's beneficial to seek Allah's guidance and express gratitude for His blessings and insights. Perform du'a (دعاء), asking for clarity and strength in dealing with any anxieties that may resemble those felt in the dream. Seeking refuge in Allah from any harm is always recommended.