It is narrated from Sayyiduna Jabir bin Abdullah (may Allah be pleased with him) that when the Messenger of Allah (peace and blessings be upon him) would come to Safa and Marwah, he would walk at a normal pace, but when his feet entered the valley, he would walk quickly until he had crossed the valley.
Imam Malik, may Allah have mercy on him, said that if a person, out of ignorance, performed sa'i before tawaf, then he should return and perform tawaf, then repeat the sa'i. And if he has left Makkah and gone far away, even then he should return, perform tawaf, and then perform sa'i. If he has had intercourse with a woman, then he should return, perform tawaf and sa'i, then perform another 'umrah and offer a sacrifice.
Hadith Referenceموطا امام مالك رواية يحييٰ / كتاب الحج / 831