Analysis:

This quatrain by Saadi Shirazi delves into the complexities of love and relationships. It's a declaration of loyalty and commitment, even in the face of imperfections.

Denial of Faithlessness: The poet begins by denying any lack of commitment to their friend or lover. They assure that their heart remains steadfast.

Focus on Flaws: Interestingly, the poet states that even if their own beauty fades or is marred, they will continue to focus on the flaws of their beloved. This could be interpreted in several ways:

Honesty: The poet values honesty and authenticity in relationships, and they are willing to acknowledge the faults of their loved one.
Self-deprecation: The poet may be downplaying their own worth to emphasize their loyalty to the other person.
A test of love: Perhaps the poet is testing the depth of their love by focusing on the negative aspects of their beloved.

Thematic Implications: The quatrain suggests that true love is not based on superficial qualities like beauty but on a deeper connection. The poet's willingness to overlook flaws and maintain loyalty is a testament to the enduring nature of their feelings.

Themes:

Loyalty: The poet emphasizes their unwavering loyalty to their beloved.
Honesty: The poet values honesty and authenticity in relationships.
Imperfections: The quatrain acknowledges the presence of flaws in human relationships.
Depth of love: The poet suggests that true love goes beyond superficial qualities.

Saadi's quatrain offers a nuanced perspective on love and relationships. It suggests that true love is enduring and can withstand the test of time, even in the face of imperfections. The poet's willingness to focus on the flaws of their beloved, rather than their own, is a testament to the depth of their commitment.