The number 7 seems to appear numerous times in Islamic text. This recent realisation has made this association extremely fascinating..
1- 7 circumambulation (Ta’waf) around the Kaa’bah during Hajj
2- 7 walks (back and forth) between Al-Safa and Al-Marwah
3- 7 heavens
4- When the Prophet (peace be upon him) was taken to heaven during Miraj he reported to have seen an angel with 70 000 heads, each head having 70 000 mouths, each mouth having 70 000 tongues and each tongue speaking 70 000 languages; all involved in reciting the praises of Allah Almighty (can't remember the reference for this)
5- 7 pebbles to be used each time for stoning of the Jamarat’
6- 70 000 angels write good deeds for one who recites durood shareef