Tafsir Ibn Kathir -> Surah Al-Isra' -> Ships are a Sign of the Mercy of Allah

Allah tells us of His kindness towards His servants by subjugating for them ships on the sea. He makes it easy for them to use ships to serve their interests, seeking His bounty through trade between one region and another. He says:

﴿إِنَّهُ كَانَ بِكُمْ رَحِيمًا﴾

(Truly, He is ever Most Merciful towards you.) meaning, He does this for you out of His grace and mercy towards you.

﴿وَإِذَا مَسَّكُمُ الْضُّرُّ فِى الْبَحْرِ ضَلَّ مَن تَدْعُونَ إِلاَ إِيَّاهُ فَلَمَّا نَجَّـكُمْ إِلَى الْبَرِّ أَعْرَضْتُمْ وَكَانَ الإِنْسَـنُ كَفُورًا ﴾

(67. And when harm touches you upon the sea, those that you call upon vanish from you except Him. But when He brings you safe to land, you turn away. And man is ever ungrateful.)