Is escaping a situation by praying or reciting the Qur'an, such as offering supererogatory prayers to avoid meeting someone, considered showing off (riya') and does it entail sin?

Combining the intention of worship with a worldly intention does not invalidate the act, as long as the intention of worship is dominant. This is not considered showing off (riya'). However, dedicating the intention purely to worship yields a greater reward.

Al-Shatibi said: "The personal benefits specific to an individual do not prevent their combination with acts of worship, except for what is inherently contradictory to them... As for what is not contradictory, how can the intention for it detract from worship?"

Ibn Hajar said that if someone intends to fast for dieting along with worship, or to circumambulate (the Kaaba) to avoid a creditor along with worship, they will be rewarded for the act of worship, especially if the religious intention is predominant.

Al-Suyuti said: "If someone intends prayer and to avoid a creditor, their prayer is valid; because their preoccupation with avoiding the creditor does not require intention."

And in "Ghamz Uyoon al-Basa'ir": "If one intends fasting and dieting or treatment, the soundest opinion is that it is valid, because dieting or treatment is achieved whether one intends it or not. Therefore, this intention is not considered a partnership (in intention) or an abandonment of sincerity."