What to Do If You Start Sa`i from Al-Marwah?
Question

What is the ruling on one who does `Umrah and starts Sa`i from Al-Marwah instead of As-Safa?
Praise be to Allah.What the one who does Sa`i between As-Safa and Al-Marwah must do is begin with that with which Allah, may He be Exalted, began and with which His Messenger (blessings and peace of Allah be upon him) began. Allah, may He be exalted, says (interpretation of the meaning): “Verily! As-Safa and Al-Marwah (two mountains in Makkah) are of the Symbols of Allah. So it is not a sin on him who performs Hajj or `Umrah (pilgrimage) of the House (the Ka`bah at Makkah) to perform the going (Tawaf) between them (As-Safa and Al-Marwah). And whoever does good voluntarily, then verily, Allah is All-Recogniser, All-Knower” [Al-Baqarah 2:158].
The Prophet (blessings and peace of Allah be upon him) began his Sa`i with As-Safa, and he said: “I begin with that with which Allah began.” The more correct view is that doing Sa`i in the proper order is obligatory. So the one who begins with Al-Marwah first cannot count his first lap, and he must do another lap. 
Shaykh Muhammad Al-Amin Ash-Shinqiti (may Allah have mercy on him) said: 
“It must be understood that the majority of scholars stipulate that Sa`i must be done in the proper order, which means beginning at As-Safa and ending at Al-Marwah. If he starts at Al-Marwah, that lap is not counted. Among those who stipulated that it must be done in the proper order are: Malik, Ash-Shafi`i and Ahmad, and their companions, and Al-Hasan Al-Basri, Al-Awza`i, Dawud and the majority of the scholars. 
Conflicting views were narrated from Abu Hanifah concerning that: 
The author of Tabyin Al-Haqa’iq Sharh Kanz Ad-Daqa’iq, which is a book on the Fiqh of Imam Abu Hanifah (may Allah have mercy on him), said:
“If a person begins Sa`i from Al-Marwah, the first lap should not be counted, because he has gone against the command.” 
Shaykh Shihab Ad-Din Ahmad Ash-Shalabi (may Allah have mercy on him) said, in his footnote to Tabyin Ad-Daqa’iq:
“With regard to his words “If a person begins Sa`i from Al-Marwah, the first lap should not be counted”, in Manasik Al-Karmani it says: Doing Sa`i in a certain order is not an essential condition, according to our view; even if he begins at Al-Marwah and comes to As-Safa, that is acceptable and he may count it, but it is disliked because he did not do what is Sunnah. Therefore, it is recommended for him to repeat that lap. 
As-Saruji (may Allah have mercy on him) said in Al-Ghayah: There is no basis for what Al-Karmani said: 
Ar-Razi (may Allah have mercy on him) said in Ahkam Al-Quran: If he begins with Al-Marwah before As-Safa, that is not to be counted according to the well-known report from our companions. It was narrated from Abu Hanifah that he should repeat that lap, but if he does not do so there is no blame on him. He regarded it as being like failing to follow the proper order of washing the limbs when purifying oneself. End quote. 
With regard to As-Saruji’s comment that there is no basis for what Al-Karmani said, that is subject to further discussion. End quote from Ar-Razi. 
The evidence quoted by the majority for it being essential to do Sa`i in the proper order is the fact that the Prophet (blessings and peace of Allah be upon him) did that and said: “I begin with that with which Allah began.” According to a report narrated by An-Nasa’i he said: “Begin with that with which Allah began,” in the form of a command or instruction. Moreover, he said: “Learn from me your rituals of Hajj.” So we must learn from him and follow him with regard to our rituals, and begin with that with which Allah began, and following that which he (blessings and peace of Allah be upon him) did, acting in accordance with the Holy Qur’an.” (Adwa’ Al-Bayan, 5/250-251) 
The scholars of the Standing Committee said – in response to a question about someone who began with Al-Marwah instead of As-Safa, and added an eighth lap: 
“If the matter is as you describe, that you did an eighth lap to complete the seven laps of Sa`i in the correct order, then your Sa`i is valid, because the first lap that you did, beginning at Al-Marwah and ending at As-Safa, is regarded as invalid, as you did not do it in the prescribed manner.” (Shaykh `Abd Al-`Aziz ibn `Abdullah ibn Baz, Shaykh `Abd Ar-Razzaq `Afifi, Shaykh `Abdullah ibn Ghadyan, Fatawa Al-Lajnah Ad-Da’imah lil-Buhuth Al-`Ilmiyyah wal-Ifta’, 11/259- 260) 
And Allah knows best.