If he walked backwards or on his hands or sideways, is his Sa’i valid?
Question

During one of the laps bet ween as-Safa and al-Marwah, whilst doing  Sa’i, I walked backwards for approximately four steps in order to talk to my daughters. What is the ruling on my ‘umrah? What must I do, noting that I have returned to Madinah?
Praise be to Allah.Walking backwards during your sa‘i does not matter, because the point is to cover the distance between as-Safa and al-Marwah, and you did that, so no matter how the person who is doing sa‘i walked, it is sufficient.
It says in Nihayat al-Muhtaj (3/292): If [the pilgrim] does seven laps, following the example of Hajar, going from as-Safa to al-Marwah is one lap, and coming back [from al-Marwah to as-Safa] is another lap, even if he walks on his hands, or he walks backwards, as appears to be the sound view, because the aim is to cover the distance. End quote.
In Fatawa ar-Ramli (2/86), it says: He was asked about someone who does sa‘i walking sideways, or walking backwards, or walking on his hands – is it valid?
He replied: Yes, it is valid. End quote.
This applies if what you mean by walking backwards is that you still walked in the direction of your lap, but with your back turned.
However, if what you mean is that you walked back a few steps in the wrong direction, so you took a few steps backwards, that does not matter either, because a brief interruption does not have any impact, even if it is said that the laps should be done one after another, without interruption, as in the case of tawaf. All that happened is that you took a few extra steps, which is a minor issue.
The soundest view is that doing the laps without interruption is not stipulated, and that it is permissible for the individual to rest during his sa‘i. The same applies if he needs to take a few steps in the opposite direction during his sa‘i.
Conclusion: what you did does not matter, and your ‘Umrah is valid.
And Allah knows best.