The Shaikh (may Allaah preserve him) said:
The Prophet (sallal laahu alayhi-sallam) was clear with everyone regarding his call. When he arrived in Madeenah -at that vicinity of Masjid Quba (i.e. which he later built as the first Masjid)- he disseminated the call with its clarity and purity; so it made the hypocrites conceal themselves and they did not receive it except by manifesting Islaam, whilst surely hiding what they hid (i.e. disbelief in their hearts). This is likewise the habit of the people of falsehood; they do not make apparent what they (truly) believe. As for the people of clarity, they are people who openly proclaim (what they truly believe); so beware of the people who hide.
[Wudooh Al-Manhaj As-Salafi. Page 13]